That's interesting, thanks for the citation. I was basing my opinion on his well-known hate of proprietary software, and his desire to make all software free. Dual licensing works counter to that, because it allows someone to use GPL software without making their own derivative software available too.
Well, it's not "GPL software", it's software that's also distributed under the GPL. That's being freely distributed at all is a win compared to most commercial software.
And in fact, it could be argued that it's better (for rms' goals) than MIT/BSD/etc, since the proprietary license will impose some restrictions on its usage by other proprietary vendors.
