I'm an OT and I can see going IP limiting physical rehab to the point that one needed to be chosen over the other. My IIP unit when admitted is 168 steps all around it (I've paced enough and have enough OCD to have counted many times) and that just restricts movement enough that anyone is going to lose some muscle unless they are up for some serious pacing which may not be the best exercise for a given injury. I've been in there where my roommate was getting PT but it was pretty limited since they can't go to a rehab gym, the walking is limited to the unit, exercises limited by needing to be done on soft beds that may not be the best support, can't use weights or walkers or anything that could be used as a weapon, etc.

I worked in a long-term care psychiatric facility for people with very severe psych illnesses and traumatic brain injuries and we were often limited by what we had to do to keep people safe versus what we might typically do in a given situation outside of the context of where I worked. For example we had to lock up those elastic bands for resistive exercise and supervise use at a close 1:1 because of someone wrapping one around her neck and pulling until it was removed by several staff members.

That's just my experiences but maybe that's what the "disruption" the dr referred to was.