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.

>>23
It's not so much direct inheritance as influence - Lisp machines were programmed in Lisp from the ground up, with only a small core in assembly. The command line interface exposed by the GNU utilities is very similar in presentation, but the implementation (C, with a C kernel) is totally different.

This is significant because a pure Lisp system would otherwise have had terrible performance on early micros like the 386. This allowed RMS and co. to keep running emacs with decent performance by ``shelling out'' to C tools with a similar looking CLI.