I have to personally disagree with this one. It really depends on which "motion" makes you sick.
Many people, myself included, feel ill on Space Mountain because it jerks you back and forth so much because it's such a rickety old coaster.
RnR, on the other hand, is a much newer coaster and rides much more smoothly - especially in the front. The first few rows are the most smooth (and since there are no big drops it's not scary like being in the front of most coasters). Plus, RnR is so short - the actual time "in the air" is only like 75 seconds.
If, on the other hand, just the forward motion of a roller coaster gets you, then yes, you will likely experience it on ANY coaster.
I honestly know many older people (parents, grandparents) who hate Space but will ride RnR. The motion on the rides is quite different.
N.E.D.