I get the desire to accommodate riders whose physical limitations have them on pedal assisted motorcycles, yet it’s opening a huge can of worms to allow them off road or off pavement. Trouble is there’s a fine line between riding on a gravel rail trail that heads down a dirt double track that turns into a single track, etc..... and I really think motor assisted cycles have no place on designated mt. bike trails.
Biggest issue is it’s really hard to tell when a motor assisted is a pedal only assist or one equipped with a throttle and as far as I know, the throttle models have significantly more horse power and as result can do more damage to trails.
And I've seen this at a local park that has an extensive mt. bike trail system, having seen throttle controlled e-bikes on the trails. When I see mud racing stripes up a riders butt and back, I know they are gunning it and doing damage that a pedal only mt. bike isn’t going to do.
And who’s around to enforce it ?, nobody really. Thus it’s going to be a problem that is easily resolved in parts by adopting a rule that ANY cycle with a motor has no place on bicycle only trails.