It isn't "no reason"...dude buys a ticket, is forced to sit in the flight attendant jump seat, then further forced to sit IN the bathroom. I don't know about you but that would have me raging mad.
I don't see where anyone "MADE" him do anything honestly.
Kinda sounds too made up too. If the attendant told me to sit in the bathroom for the rest of the flight, i'd say no.