I don't see anything wrong with what Blow said.
He didn't like the contract terms, so he didn't accept them. Like it or not, he IS a big name in the industry, and given that his game will probably be getting significant exposure on Steam's front page anyway, he has no reason to bother arguing with smaller distributors over contracts. That's not being an asshole, that's just the smart thing to do. Frankly, I would think GOG has more to gain from distributing The Witness than Blow does.
If this were about a developer refusing to distribute through Steam for similar reasons, everyone here would be applauding.
Smannesman: I think I read once that GOG has some kind of NDA incorporated into their contracts or something like that.
Dalswyn: But then, wouldn't most publishers (and countless businesses as well) have those?
As far as I know, yes.