I think you’re putting too fine a point on it. He did what he had to do to accommodate a very evil man during a time of pressing need, and based on my reading of his remembrances, Roosevelt had nothing to do with it. However, “suck up” is undoubtedly too harsh a term, since it implies obsequiousness. Whatever the case, I would have done the same, assuming I were as perspicacious as Churchill at the time.
You may have to define two words - and you know which ones they are - to make you post understandable to PaleoBob and other Galloping Neanderthals.