Usually PT defers to the ortho. After all, we work under their orders. Once the PT is informed of the ortho's decision to ok riding outside it really shouldn't be an issue at all.
PT is just a stepping stone to get people back to their usual activities. Once a patient is back to their usual stuff, I kind of go by a 90% rule: if they have 90% of their ROM, feel 90% improved over all, and have eagerly returned to activity; I kick 'em out the door!
At that point, they know as much about rehabbing their injury as I do and usually if that remaining 10% is going to come back, it is during full return to activity. Activity is better than PT at that point. They continue with their home exercises and I call them in a month. If they feel like things are even better a month later, I discharge their chart.
Hips can be funky, because the ORIF surgery and nature of the break can sometimes build in a limitation or two, but his ortho would have told him if he didn't expect full ROM.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson