"Where hustle's the name of the game

And nice guys get washed away like the snow and the rain;

There's been a load of compromisin'

On the road to my horizon

But I'm gonna be where the lights are shinin' on me …"

Glen Campbell Rhinestone Cowboy (1975)

If you wanted to design the least threatening figure in popular culture, you might come up with Ed Sheeran, now Glen Campbell is long gone. He sings love songs, plays guitar, avoids political grandstanding and has somehow become one of the biggest musicians on Earth without constructing his career around outrage. Apparently even that is no longer enough.

Sheeran's American Loop tour has been thrown into turmoil after rapper Macklemore used his supporting slot at MetLife Stadium to make an explicitly pro-Palestinian intervention. He called for a "Free Palestine," showed political imagery and performed his protest song Hind's Hall. Some Jewish and pro-Israel organisations objected, and subsequent venues indicated that they would not host the tour if Macklemore remained on the bill.

The tour promoter, Messina Touring Group, removed Macklemore. Sheeran subsequently stressed that this was the promoter's decision rather than his, saying that he had attempted to find a compromise with promoters, venue owners and activists on both sides. Macklemore himself acknowledged that Sheeran had been put in a difficult position.

That should have been the end of it. Instead, the cancellation machine changed direction. The remaining support acts began abandoning Sheeran's tour in solidarity with Macklemore. Finneas, Lukas Graham, Aaron Rowe and Beoga all withdrew. What began as a dispute over whether an opening act could turn somebody else's stadium concert into a political platform became a test of Sheeran himself. His offence was increasingly that he would not take the required side.

Sheeran eventually issued a statement saying that he was appalled by the Israel-Palestine conflict and regarded the suffering on both sides as a human tragedy. He added something that ought to be completely unremarkable: he has personal views, but does not believe he is obliged to express them publicly.

There is the real heresy. Modern celebrity culture increasingly assumes that possessing an audience creates a duty to convert that audience into a political constituency. Actors must instruct us about elections. Musicians must pronounce upon wars. Sportsmen must settle moral controversies. Silence is no longer silence. It is interpreted as complicity. Even neutrality becomes suspicious.

Sheeran's position is especially interesting because there is little evidence that he simply does not care. Robert Kraft has said that, before Macklemore publicly challenged him over humanitarian donations, Sheeran had privately asked Kraft to match a $2 million donation for Palestinian humanitarian assistance. Sheeran was apparently willing to put substantial money towards helping people while declining to make his concerts political rallies.

That ought to complicate the caricature. There is also nothing inherently illegitimate about Macklemore expressing political opinions. Musicians have been making political statements for generations. Nor is there anything illegitimate about other musicians deciding that they no longer wish to perform on Sheeran's tour. The revealing part is the assumption that Sheeran himself must choose a public political identity because the people around him have done so.

That is where activism begins turning into compulsory ritual. The argument is no longer merely: Here is what I believe about Gaza. It becomes: You must tell us what you believe about Gaza, and your answer must satisfy us.

Sheeran's concerts are particularly strange places to demand this. His audience includes families and children who have paid considerable sums to hear Perfect, Shape of You and Thinking Out Loud. They have not bought tickets to attend a seminar on the Middle East.

That distinction matters. A society in which every cultural activity becomes political eventually leaves people nowhere to escape politics. Music, sport, films, restaurants, universities and workplaces become additional arenas in which everyone is expected to advertise the correct moral commitments. The demand also destroys something that pluralist societies badly need: the right not to declare.

You can care deeply about Israelis and Palestinians without putting a flag on your social-media profile. You can donate money without announcing a geopolitical doctrine. You can believe that terrible things have happened without pretending that a pop singer possesses the solution to a conflict that governments, diplomats and armies have failed to resolve for generations. And you can simply believe that a concert is a concert.

This is why the Sheeran affair is bigger than one tour. The politics of compulsory declaration has gradually eliminated the middle ground between endorsement and opposition. If you do not repeat my slogan, you are presumed to support my enemy. That is not tolerance. It is a loyalty test.

Ironically, Sheeran may be doing something more genuinely pluralistic than many of his critics. He has not attempted to prevent Macklemore from holding his views. He says Macklemore was allowed to choose his own set. He tried to negotiate when venues objected. He has acknowledged suffering on both sides and apparently donated substantial money towards humanitarian assistance. What he will not do is transform himself into somebody else's political billboard. That is apparently enough to make even Ed Sheeran controversial.

There was once a fairly useful liberal principle that people could disagree about politics and nevertheless work together, listen to music together and occupy the same public space. Increasingly, the activist mentality reverses the proposition: agreement on politics becomes the entrance fee for everything else.

Perhaps that is why Mr Nice Guy makes such an interesting target. There is little pleasure in cancelling somebody who already enjoys political combat. The real demonstration of cultural power comes when even the harmless bloke with the guitar is told that keeping out of politics is no longer an option. Ed Sheeran's answer, so far, appears to be that it is. Good for him.