Yeah, but even Stallman's opinion and understanding on the matter has changed over time (that was one of the first GPL enforcement actions). IIRC, FSF was one of the amicus briefs in favor of Google's position. They want to be able to replace proprietary software with compatible, open source clones piece by piece.

In fact a good chunk of the case law cited today hadn't even hit the courts yet at the time Stallman made that statement.