Obviously a reception isn't much different than a carry from the standpoint of how likely you are to get hit so you'd have to add those to the number of rushes (for both the RB and QB, if applicable). Adds a lot more exposure to hits on the RB.

Additionally, picking up a blitzing linebacker can be a pretty significant impact. They would be able to brace for the contact better than a QB who just released the ball, but I'd guess that a RB that played every down would take more hits in pass protection than the number of hits on the QB they're protecting.

Another factor is that a RB's carries are generally more likely (in my opinion, don't have any type of stat on this) to be between the tackles and running full-steam into a linebacker. A QB will have many carries from scrambles that will be in more space with a higher likelihood of stepping out of bounds at the end of the play rather than taking a hit. I'd guess that the percentage of rushes "in space" for a QB is a good bit higher than the percentage of rushes "in space" for a RB.

Not saying that I absolutely disagree, but I'm not sure that I'm convinced one way or the other.