Edit: I say this a cyclist myself. I see other people on bikes do some dumb shit, we can't say they aren't real cyclists because they do something that makes us look bad.
However, e-bikes can give unconditioned people “superhuman” strength and endurance. Physical training tends to give individuals intuitive limits for personal safety, but using a modified e-bike short-circuits this intuition.
I am thinking that limits on stuff like diameter of frame tubing or tire width (which would not stand up to riding at speeds outside of normal “human” parameters) can help.
He took it up to 40 MPH (on his own private land) before chickening out. The chain would simply not stay on the cassette at that speed. He reckons that if you did drive it to the limit, you'd go through a brand new set of disc brakes and calipers in a week, if you didn't manage to boil half the hydraulic fluid off in the mean time!
But to a non expert this thing looks exactly like a regular bicycle--because it is (or was, before it was illegally modified to be a motorbike).
I like e-bikes, they are getting more people to ride bicycles, and I’m especially seeing a surge in older people getting out and riding far. This is a good thing for all cyclists. But parent is correct: e-bikes are motorized vehicles. There are bicycle trails where I live where motorized vehicles are not allowed, and that includes e-bikes, and it is enforced.
You have identified that they give cyclists a bad reputation, and we all suffer due to it. :(
Cyclists who behave badly are cyclists. People riding vehicles with motors that let them go that fast simply aren't cyclists. We don't call ICE motorcycle riders "cyclists" in that sense either.