ESR is either unaware of the facts or being disingenous for rhetorical purposes. Fact of that matter is that GCC has supported plugins for a long time and carved licensing exceptions for such plugins to make it palaptable for other purposes. Example,
There are interface issues and other technical problems which need to be fixed and GCC developers are well aware of that. ESR's post doesn't seem to serve any real purpose other than to flame and misdirect the conversation.