Fair assessment. Those who are too old, too young, impaired or too scared (I don't mean this negatively, of course) to ride Universal's attractions will find more reason to go to Disney. In that respect, all else equal I think Disney is pulling from a larger population of potential guests.
As far as whether Disney guests are thrill seekers or if they want to ride every ride, I think Disney guests are pretty diverse. Some of them like thrill rides, others do not. In terms of quality though, at similar thrill levels, Universal seems to boast the superior attractions right now. Per park at least. So for guests who can do all the rides at both, even if they only get around to a few then Universal is probably the better option.