I don’t think this guy will get any prison time. Perhaps a day or two in holding as he’s being processed. And that’s it.
Please see my post #7.
He might get a slap on the wrist if he did this on a bus or a train, dealing with a municpal transit agency, but when it comes to commercial airliners, the authorities will come down hard on him.
Acting up is bad enough but assaulting a flight attendant is a whole other level.