I'll add my $0.02.
One small bit of knowledge- in our neck of the woods, the University of Minnesota is known as "The U". Yes, I know you have your own "The U" in Florida, but we all affectionately refer to ours as "The U".
From an outsider's perspective, relying on the train seems like a good idea. However, it has it's limitations. It's SLOW as it's at grade and has to stop at lights occasionally. As others have stated, outside of daytime hours it can get a bit squirrely, usually because there is little policing of people paying before they get on; it's basically the honor system. If you want to rely on the train, I would focus on the apartments along University Avenue between the Minneapolis campus and St. Paul (so east of campus). Short ride to campus, should be reasonably safe, and likely cheaper apartments than directly adjacent to campus.
As others have stated, parking on campus isn't great. It is very much an urban campus, and parking is priced (with availability) accordingly. If you don't have a contract spot, ramps often fill up by mid-morning. So dependent on his schedule of when he needs to get there, he could be parking out a ways or trying to find street parking.
It will be more expensive, but getting an apartment near campus IMO is worth the cost. You can live a bit farther and get a bike or electric scooter and save the hassle of parking your car. Another option to consider is a place near the St. Paul campus. The Minneapolis and St. Paul campuses are not directly next to each other, but are connected by a transit way with free University buses. Takes 10-15 minutes on a (free) bus to get from - campus to campus, depending on which stop you're going to. Used exclusively by students, so extremely safe. Housing near the St. Paul campus is a cheaper alternative. If he's going to be on campus for the majority of the day (not a lot of back-and-forth), this could be a good option.
