I suppose that they should "gear up" for Allen to start day 1. I hope they "gear up" every player to start from day 1. He did get blanketed by Dabol yesterday & that's a good thing.
Devil's advocate to your points above would be that Allen sits (mostly) this year. (I do think that this is the preferred plan of the coaches) That gives you next off season with tons of cap space and another draft to purchase those weapons for Allen.