Just tried my 5D and my 1DnkIIn with flash in manual and camera in P mode. I get the same thing you do. 200 @ f22 or 250 @ f22 with the 1D. These two camera bodies both came out at the same time.
I am not sure why you would want to operate in P with the flash in manual? I cannot imagine you getting a good exposure. If the flash is in manual the camera needs to be in manual.