MIT is under no legal obligation to continue to endorse a professor who used his position there as a platform to harass others. I don't see where you're getting "illegal" or "criminal" out of this. (And "without trial" seems like an odd way of describing what the linked article indicated was a pretty thorough internal review.)

Personally, I find a measure of real justice in MIT punishing Lewin for degrading the MIT name by taking what steps they can to deflate his academic legacy. It's the only leverage they have, and it's powerful.