Everyone with a suit, whether it be just a head, or a full drop-crotch plush fullsuit, is allowed in a headless lounge. Any con that says differently could have a lawsuit on their hands if someone passes out from heat exhaustion because they weren't allowed in, and they didn't want to take their head off around public eyes. If the con doesn't allow people with a partial or even just a head into a cool safe space, then I personally wouldn't support them by purchasing a badge.