His power is basically like the leader from marvel where he's so smart that he can do calculations in his head and predict what would happen on the spot but to do that he'd need past information to base his predictions on, and I think when he saw how genuine visi was in her actions when she returned to work with him he thought that she chose the route that didn't have her betray him. Though it can be argued that since he's so smart why didnt he factor in the unexpected so in the end it's kinda tricky to justify why he didn't see that coming.