i completely agree with all your logic to this point in the thread. it is very sound reasoning but there is another argument that can be just as sound.
at 3-7 the season is essentially over. starting Allen is not the worst thing that could happen and actually is probably one of the better ways to finish out the season being that it is lost anyways. first, we will be able to see if he makes any progress by the end of the year and should have a good handle on whether or not we think we need to address the QB position again. if it is deemed that we may need to reevaluate the QB position, Barkley should get the opportunity as he is not going anywhere. he has displayed enough to at least have a roster spot for the foreseeable future.
i'm not sold on Allen either, but we have to find out if he is it or not if we are to ever leave this purgatory we have found ourselves in for last 18 years.