I figured that was pure cope since it's not like her school uniform was in love with her either. They never mentioned that being a requisite, and in fact the aquarium trick was entirely a mental exercise in make-believe for a couple seconds so that's pretty strong evidence to the contrary that the rules aren't that nuanced.
So either it was because Asa was holding back mentally (like she needs to actually accept that sacrifice but she'd prefer to go on a date) or because other devils can't just wiggle their fingers at the chainsaw devil and make him disappear. The latter seems more obvious but they could get a scene out of the former so I could see it coming up.