I was also at Sun in '91. Michael Tiemann worked there for a while, on gcc.
Prior to my time at Sun, I'd made contributions to gcc, gdb, gas and emacs (all in support of the Convex architecture) before my time at Sun. (My former boss from Convex was the president of BSDi, too. Most of the engineers from Prisma, his company between Convex and BSDi, came to Sun when Prisma folded, becoming the early version of Sun's RMTC.)
You do some disservice to rms here. Easy enough to understand (rms is easy to dislike).
By 91, GNU had a compiler, and emacs, both of which Linus used to develop his kernel.