They would be crazy to play Allen behind that OL and get him killed like David Carr. I'm not against starting rookie QBs, but don't do it if you can't protect them. It isn't like they are loaded with talent at the skill positions either. The only one that's any good is a 30 year old RB that could get suspended at any moment.
Besides, Peterman flat outplayed Allen in the preseason. I don't have a high opinion of Peterman, but he did earn the starting job.