This is a terrible idea that people will just not let die. This is something you do if you are uncommitted to your starter, or feel he needs a push, which is probably the same thing. Regardless of how some around here obviously feel, that is not the case with the Bills. Beane is right in saying Cam will not, and probably should not accept a backup position, and the bills job is simply not open to competition. That would be the absolute worst way to develop Allen at this point. Creating controversy at the QB position does not help them in the least. Cam creates controversy.
All that assumes he can even still play at a high level. It has been quite some time since that has been the case.