He’ll have Secret Service agents guarding his body. I’m not sure Rikers could withstand those guys, let alone hurt Trump.
I don’t think he’d do well irrespective of his personal physical safety. It’s not a stretch to say he’s a proud man and being there would likely take an emotional toll.
Just wait until it gets to the point where they decide to jail him for violating the order and Biden rules that he doesn't get SS protection any more. Sure, it may be illegal to do so, but what's stopping him?