I don't follow the compilers very closely, so my recollection may be fuzzy, but I think this is what the grandparent was getting at:
In the past some people have proposed giving GCC a clear, serializable intermediate code so that one could use GCC front ends and back ends independently of the rest of GCC. The leadership viewed this as an end run around the GPL, because whatever produced or consumed this intermediate code would not need to link to the invoked portions of GCC. Tight coupling between the front ends and back ends was therefore treated as something to be encouraged for licensing reasons.
LLVM's design by contrast centers around its bytecode. Since it has a BSD-like license the question of whether you link to the compiler's code or fork/exec it is unimportant.
Since the emergence of LLVM, it's my understanding that the GCC leadership have softened their views -- the alternative to invoking GCC in a separate process is now to use LLVM, rather than to link to GCC and release one's source code; thus purely technical concerns can determine the design of GCC also.