[GrinningFool]

Implied ownership claim is not a legal claim to copyright, and I don't see how the author alludes to it being so.

Aside from that - well, it was a pretty rude move, particularly in that they didn't bother to acknowledge him when he talked to them (albeit over twitter) before ranting about it.

I don't think there's a question that the conference can do this legally, but they're still being ass-hats by ignoring it (and getting his twitter account suspended).