422.33 and 430.109 both say a cord and plug MAY serve as the disconnecting means. The code does not say it HAS to.
When it comes to the listing, as a general matter, the UL listing for the cord is completely separate from that of the appliance. Indeed, one of UL's constant headaches is unscrupulous manufacturers putting a UL listed cord on a non-listed appliance ... and letting the customer think the whole thing is UL listed.
More to the point, there are a variety of UL listed cord grips, evaluated for use on exactly this sort of cord.
This is a free society; something is assumed to be permitted UNLESS it is prohibited. Not the other way around.
Granted, the NEC may say somewhere in it's hundreds of pages that you can't hard-wire something that came with a plug .... but I'd like to see that citation.
