Purdue has done the precisely correct thing, pragmatically. By asking the NCAA for advice, and the NCAA responding, essentially, that this is an ongoing investigation which cannot assign conclusions yet, Purdue can play Marve without fear that it jeopardizes their season, whether Marve is included in guilty verdicts at the end of the process or not. Any school with Miami transfers should do the same.
Miami's own situation vis-a-vis the NCAA is different because they are the school investigated. Whether they play certain players or not, they will still be screwed as a program if the NCAA finds against them. They COULD choose to roll the dice and NOT play the "rumored" [at this point] players still around, in hopes of looking like better guys to the NCAA and getting slapped less, but then they risk punishing a player who might later be found not guilty. I'll bet Miami has asked the NCAA for advice on this, too, but we'll probably not hear of that "closed session".