How can a professor who has signed The "Cost of Knowledge" pledge review papers without having to recant?
Sounds like he's sticking to his moral principles, which is the best anyone can do. Maybe he could evangelize his opinion more to increase the impact of his crusade, but that's about it.

I disagree with the insinuation that he may be doing his field a disservice, since moving away from the ancient publishing model is a good thing for any field in the long run. Besides, it's not like he has left the field; just a small part of its publication scene.

Just because nobody seems to be following him (yet) does not mean he failed in any way.