I know, right? He blames it on her being "truly hated by the gods" but he's the one arranging for it to happen. He could just hide the book to be discovered after the festival.
Or better yet, notify Alina first, maybe get her permission while filling her in on the circumstances, and then go from there.
That's if that GM of the information guild ever gave him a chance to think about it first, of course, though pressuring him to make a split-second decision like that, I can't help but think she's somehow involved with this mess, as well. I mean, who better than someone from an organization specializing on intelligence gathering would go around spreading rumors about a possible way to acquire divine skills through hidden quests? Why would they go to such lengths instead of just attempting to go there, themselves, I don't know, but if adventurer's guild GM saw her as someone to keep on your toes around, she's not someone you'd want to trust with certain secrets.