If you are polymorphed into something that is not omnivorous, you should be affected by those dietary restrictions - for instance, if you are polymorphed into a herbivorous horse, you should only be capable of eating non-meat food; if you are polymorphed into an obligate carnivore like a tiger, you should only be capable of eating meat; and if you are polymorphed into an inediate form, you not only don’t need to eat, you can’t.

Permafood is explicitly inedible in a polyform unless your polyform is flagged as omnivorous.