Always an interesting thought...but doesn`t really make sense from a RP point of view. Guardians are supposed to be protecting the galaxy and stuff.
and even if they could. They`d have some pretty terrible UW ships. Low range, non availability of multiple dmg ships = they`d get owned pretty badly even if they tried :P
Also, this would require major changes to game coding. I recall the admins saying that even they couldn`t find a way around game coding to allow guardians to UW (it`s hard coded in the game that they can`t)