Okay, yeah, it does force you to pick it. I mean, yeah, it gives you chance to cancel picking it, but if you do that, you can't get to next turn as culture upgrade button replaces end turn button and even pressing enter just goes to back to skill tree. Mantis time!
Weirdly enough, thoraxians didn't go zerg on me O_o; Do they do that after you have picked second skill, is it a bug or was it because I'm friendly with thoraxians because of my embassy?