Can't put my finger on the code section, but I think this has more to do with the fact that even a window AC unit, once installed, is not really a portable cord & plug connected load in the same sense as a lamp, radio, etc. A technical stretch maybe, but it is not terribly unlike a dishwasher that is shoved into a cabinet abd plugged in (except the obvious fact there is no water connection).
I agree that it's unrealistic for the manufacturer to presume someone is going to install a new receptacle and circuit for a 4.8 amp unit. But that's probably where the requirement comes from. If I can find the NEC article, I'll post it later.
Radar
