But wait. That leads to a weird situation. That ruling suggests that if you cast Dispel Magic on an enemy, you will, unwittingly, dispel magic jar and kill them instantly if their body is more than 100 feet away. That doesn't seem in keeping with the spirit of the spell.
You're right, but that's still how the spell reads!
There seems to be a lot of potential weirdness and quite a bit of danger associated with this spell.
Keep in mind, rather than dispelling it, you could potentially coup de Gras "yourself", or have a party member do it for you, and kill the enemy that way anyway. You then jump back into the jar (well, with a successful save, otherwise you die too - thems the breaks). As I said, this spell introduces some serious weirdness.