Not that Brett ever saw that.
You can be paid for customising and extending GPLed code. The GPL really only takes effect if the program is then distributed.
The kindest impression of Brett's view (at least as he 'communicated' it; I'm stll dissappointed that he calls people 'trolls' if they ask for explanations of why the GPL is bad that don't depend on Stallman's 'intent' or his own 'pundithood') that I can take is that the GPL is 'bad' because it doesn't give developers the ability produce (only) a modified binary and get paid as if they were the sole authors of the entire work.