Sorry to hear. Just asking, why did you choose MIT license over something like GPL? It's not that they couldn't have copied you, but you would be in a different position vis-à-vis them now.
I would've chosen GPL personally, but a prototype repository already existed under MIT by the time I joined as a contributor through the fellowship. Alas.
No, unfortunately. In this era of AI rewriting entire projects from scratch, copyright protection for software is effectively dead.
Regarding attribution, I guess he is one of the copyright holders, so his name should be included in the new license. Unless we are talking about MIT-0.
Im not an expert on these things, but I think there is another type of attribution, that I guess is what the commenter is more concerned about, and that is academic attribution. It is part of academic culture that you attribute significant influences in the articles you write. There are no licenses as such for this, as far as I know. You do it because that is what you do in academic circles. If you dont, you are not in the club.