Just let them piss.
They actually do let bus operators randomly stop the bus at rush hour to pee in some cities. In Ottawa (Ontario), for instance, as long as an operator is within their 5 minute "late standard" window, they can stop and make a quick pee break or Timmy's break as long as they keep the bus in time.
The busses lock down with a PIN when they get out of the seat (generated that morning at the depot) so you can't take it out of neutral anyways to try to steal it.
https://www.michaelsuddard.com/2013/03/oc-transpo-condoned-t...
(Best part is this old blogpost with someone cranky over the stop as well getting shown receipts by OC Transpo that their Tim's wielding bus driver that morning was in fact running on time based on GPS data.)