Rory knows that in golf, Trump is a regular guy
There was a fine documentary shown on RTE about five years ago, called You've Been Trumped. It told the story of Donald Trump's efforts to build "the greatest golf course in the world" near Aberdeen, a project which would require the removal of various impediments, including the modest croft occupied by a local man who - according to Trump - "lived like a pig".
It was something of a shock to our delicate European sensibilities at the time, to hear Trump declaring that you couldn't possibly expect millionaires to be looking out of their hotel at this "horrible, horrible slum", a line which would have seemed undiplomatic coming from some corporate shyster in a cartoon - though now that he is the US President, it seems quite normal.
Then again, even at the time, you couldn't really argue that he was saying anything that went fundamentally against the country club ethos which still prevails in the higher echelons of the game of golf - and in some of the lower echelons, too.
When I am enjoying Sky Sports' coverage of the PGA Tour, I don't see many "crofts" out there on the tracks that they play; I see only mansions.
Most weeks, I see an interview with the CEO of the corporation that sponsors that particular tournament, in which the top man describes the charitable contributions they have made to local hospitals and the like on top of the sponsorship, at which point the commentator argues that a proper health service should, of course, never be run on the basis of mere charity dispensed at the discretion of businessmen.
Well no, the commentators don't say that. Indeed, I doubt if any of them have ever thought of saying such a thing, or have ever known anyone who would think of saying it, so natural is their obeisance to the cult of the almighty CEO, which is matched only by their unquestioning devotion to the military.
If you are sometimes baffled by the apparent extremism of the "conservative" people of America, you need to be watching some of these golf tournaments when they pay tribute to the military by having an actual soldier tending the stars 'n' stripes flag at a certain hole, standing proudly as the professionals walk off the green, receiving a greeting from the reverential pro, usually "thank you for your service". There is absolutely no doubt that if a player decided he would conscientiously object to this convention, that he would make a principled statement against it, however reasoned or respectful, his protest would be viewed with all the empathy of the committee at Augusta National ruling on the membership application of Malcolm X.
In this environment, Trump is normal - the only abnormal thing about him is that he says in public and without embarrassment that millionaires can't be expected to look out of their beautiful hotel rooms and see horrible, horrible slums, or that some poor person "lives like a pig", which actually places him on a slightly higher moral plane than the majority of golf's ruling class, because at least he's being straight about it.
In John Feinstein's book A Good Walk Spoiled, he recalls that of the USA's Ryder Cup team in 1993, "there wasn't a single member who had voted for Bill Clinton in 1992. The politics of the team were probably best summed up by US Open champion Lee Janzen, who said: "where I grew up, you were better off telling people you were a garbage man than a Democrat".
So Rory McIlroy had a choice - he could have refused to play with Trump, but in golf's "conservative" culture it would have created the kind of hapless fury directed at John Lennon when he muttered something about the Beatles being bigger than Jesus Christ.
Rory would also know that it is enshrined in golf's traditions that sometimes you have to play with people you wouldn't necessarily choose to be with; you just have to get on with it; you might even find that you learn something out there. Which is another way of saying that the only way to avoid running into some of the worst men in the world on the golf course, is to give up golf. This was essentially the proposition that was placed in front of him - if you find it unconscionable to be playing 18 holes with Trump, you'll probably need to get out of this game, given all the other things that are unconscionable, and given that Trump is certainly no more right-wing than the Ryder Cup team of 1993.
This was the deal for Rory - play 18 holes with Trump or be regarded by most of your peers as some kind of an enemy agent. Or, at the very least, "a garbage man", though it is not entirely clear what is so wrong with being a garbage man, as such.
But that is an issue for another day, for now we are learning that Trump's vision is most perfectly realised in the culture of golf, to the extent that he is literally running America from his track at Mar-a-Lago. It is a vision populated mainly by rich white men who have no souls, just the desire to celebrate all that is great about the game of golf, and about themselves.
A vision in which you can call some big star, and make him an offer he can't refuse.