I've had this happen a few times and handle it just like I would any other time I was on a pedal bike. Just let the rider know there is no pressure and just keep it rolling. I get the idea that most think emtbers are dicks, speaking for myself I am not and would imagine the same for most.
I give credit to
@Captain Brainstorm and
@Monkey Soup for participating from the beginning of this thread with an opposing view.
Keeping it cordial and debating. The theme is you need to be broken to apply is one of the main factors for me as much as I hate to admit it. 30+ years in this sport and 2 bad knees from working construction has brought me here. Thank God for a little assistance because last time I rode my pedal bike my left knee blew up like a pumpkin.
I'm too old yet too young to retire with 2 kids in school to have my knees opened up and miss time from working. As hard as I pushed my ebike I haven't had an issue with either of my knees. Pretty sure between construction and SSing only for past 12 years pushed them to a limit of no return. Again as I said before I'm riding stuff I never would have before and having more fun doing it, and that's really what it's all about.