Why did GNU choose UNIX?

Or rather, why did rms et al dislike UNIX? It seems to come up a lot that they basically settled for a UNIX clone since it was widespread. They certainly didn't care for the philosophy.

Well... It WAS widespread... what were the alternatives? Make something brand new so people would be even extra cautious to try it out? And I don't think they were consciously against the philosophy, probably just thought it sounded good and later on swayed from the path in accordance to popular demand.