Earlier quoted context omitted.
Obnoxious or not, I think the point of contention is whether a theme can considered a derivative work or not. I think you can easily find lawyers who would have no trouble arguing either side of the case.
So find me a lawyer (more than just a blog post) who have successfully contented against such a case. Did you watch the whole interview? His views has nothing to do with laws, nothing to do with grey areas within the license (from my understanding GPL is very explicit about this); he basically said "I don't wanna do this because, I don't wanna do this." How can you rationalize with that?
EDIT: Not many licenses have been challenged in court, including the GPL. Do you have any cases to cite in favor of GPL?