An ebike weighs less than a motorcycle by at least half (for super lightweight motorcycles) or less than 1/6th the weight. So a fast ebike is about as dangerous as merely the human person +100lbs traveling at speed.
Thus, less energy to transmit to a pedestrian
100 pounds of bike plus 150 pounds of person hitting a pedestrian at 30+ mph is still going to do cause serious injuries to both of them.
But it's really a moot point because there are essentially zero motorocycles travelling on sidewalks, bikepaths, and trails where pedestrians are going to be concentrated, while it's a free for all for e-bikes.
In general, motorcycle/pedestrian accidents are pretty rare. Statistically, motorcyclists are most likely to injure or kill themselves rather than bystanders.
Yeah, it's not going to be as bad as a 300lb bike and 150lb person with a fuel tank in the back...
There are lots of gas powered motorcycles in the bike lanes where I live. Not legal, but nobody enforces it.
And still fatal
https://www.ctvnews.ca/vancouver/article/pedestrian-dead-aft...
In this case it was a bicycle and not an ebike. That said, anecdotally, many ebikes I see regularly travel faster than the people powered versions