One thing my D did which may or may not be helpful, is set up a separate bare-bones Instagram account that she used to follow the colleges she was considering. But not just the “official” college account, also the accounts for student orgs she was interested in, campus event boards, the career center, the cafeteria, anything she was interested in seeing more closely. It’s obviously an imperfect window, but it does offer a window into the vibe and activities that happen on campus throughout the year. You can also sometimes catch some interesting insights in the comments. 
Overall it sounds like he has a good plan with attending admitted student days, my D also went that route and I think it helped solidify her decision. I agree that the “wooing” done by admissions can be a bit of a smoke screen he should try to look beyond. Some schools do it, some schools don’t, and truthfully I don’t think it’s personal unless they’re giving extra money. 