In the follow up email (sent after the ban, and with a helpful "Please upload a new one", which I cannot do because it's restricted), they cite that "profile photos can get flagged for: (...) Not being an image of you or an actual photograph".
That actually seems fair to me, considering what LinkedIn is.
It's pretty normal to ban people instead of trying ro fox the issue. It's probably cheaper to them.
We have no rights and no protection from corporations other than "Do business somewhere else"