I think there may be less to “get” here than you are hoping for. You need tempo and meter together to make any sense, and you’re correct to point out that specifying tempo without meter makes it a bit meaningless, but I infer from “dance music” that we’re talking about 4/4. That being said, it’s not at all unusual to use polymeter and polyrhythm in dance music, so you could certainly stretch the meaning of things however you wish. They just might not play your track if it feels “wrong” somehow.
I suppose they could have said “larghissimo” but that might have been even more confusing.