What does have legal liability is an act of god clause. If any sort of language like that is in whatever's being signed this situation certainly qualifies.
A force majeure contract absolves them of delivering their service. It doesn't mean they get to change their service however they see fit and keep all the money.
People up front for an in person semester. If they really want to go the force majeure route, they should return the money up front and renegotiate the rest of the semester.
Sure, they can return some money but who knows how much was already allocated, especially with distance learning continuing. I got no refund from my kid's preschool for similar reasons.
Doesn’t mean universities lose the case, but whether or not they spent the money is irrelevant.