And it's not because I think he'll do a better job than Griffin, in fact I don't think Cousins will do quite as Robert. But the season is essentially over so it would make sense for the following reasons: 1. Give Cousins more gametime reps so he's better prepared for next season. 2. If he performs well, he increases his trade value.
I don't see any downside to this other than the fact that it would piss off RGIII who is ultracompetitive and wants to play to the very end. And of course there would be a media firestorm that would ensue.