here’s Mayor/Kilmartin/Enright’s fairly alliterative take on it (p. 123):

“[. . .] I could not arrive at detachment. That of M. de Charlus was complete. And given that he was nothing more than a spectator, and that, without being genuinely French, he was living in France, there was every reason why he was likely to be pro-German. In the first place, he was very intelligent and in every country fools form the bulk of the population; no doubt, had he lived in Germany, the German fools defending foolishly and with passion an unjust cause would have irritated him; but living as he did in France, the French fools defending foolishly and with passion a just cause irritated him quite as much. The logic of passion, even if it happens to be in the service of the best possible cause, is never irrefutable for the man who is not himself passionate.”