if one can show it is sanctioned behavior of the frat
(which i think we can all safely assume it was).

and i think it makes sense to expel any kids caught on camera singing.

but were i representing a random kid on that bus
i would say the school has no factual basis for expelling my client simply because he happened to be on a bus (or in a fraternity) with racists.

expulsion is a pretty high consequence, so imo they need a lot more than "we heard a lot of your homies singing so you probably were too".