I think this is basically correct, although ebikes shift the distribution rightward -- the average rider+bike system is marginally heavier, average speeds are m

I think this is basically correct, although ebikes shift the distribution rightward -- the average rider+bike system is marginally heavier, average speeds are marginally higher -- at the margin, someone is going to be unable to brake to prevent a collision they would otherwise be able to. But it's also true that heavier riders on manual bikes should often consider brake upgrades.