Especially cuz of how he throws. Even just in the pocket, he has a tendency to not have his front foot planted completely when he throws it. I think he's actually fortunate in this sort of situation as he's not reliant quite as much on that part of the technique.
Thanks for bringing that up, as I heard a commentator mention it this past week. I wonder how/if this is a deteriment to him. Thus far, little has been said about it, so I'd assume no. However, he has a cannon for an arm, could it improve if he was planting that foot?
There's also another quote from RGIII basically stating that he's not just a running QB and that if he needed to be less mobile and more of a pocket QB (due to the injury), he'd be fine.