Bungie's writers are lazy and unimaginative. The Wolves could 100% stay somewhere on Earth, Moon, and Venus but they are too stupid to think how to do it. I mean, except for maybe the Moon I can think of a spot each of the head honcho Wolf guys could "retreat" to. Like on Earth, the guy in the Divide could go inside the Dock area or Breach (or outside where you start). On Venus all the Wolves could retreat to near the Ketch area. Spread out among that HUGE area. The moon is harder, but I'm sure it would not be hard to figure out. Put a general near those mini-bounty targets. Simple. Bungie is just lazy as hell.