If the front end and back end can be separated cleanly, then a company could put their proprietary compiler back end behind the GCC front end without violating the GPL. Stallman has always worried about things like this; his objections to virtual machines have a similar basis.

That sounds like the same strategies used by proprietary software companies who go through all sorts of loops to discourage uses that don't ideologically fit with them. Almost like Free's version of DRM.

Wow, and this is stated explicitly? Seems like cutting off the nose to spite the face. I guess ideology is more important than code quality to the FSF. They have every right to do it, of course, but as an outsider it seems counter-productive

Witness the saga of ECGS -- people had to fork GCC because the FSF refused to take patches from the community.

The FSF's concern was to have employees maintaining (and controlling the development of) the software and as far as they were concerned that was that.