Of course he won't say why he dislikes her. The answer to a lot of his questions is "yes", and Pops here is probably just gonna interrogate him about her or something and make him more resentful before the cycle repeats itself.
The guy is being a dick, but I understand where he's coming from. Deep-rooted issues like that don't get solved with just a "stop being an asshole". At least he feels sorry about it.