You'd have to run some kind of loop: create an possible position for the explosion, then check that that position was more than say 10 yards from any of the loons you care about. If it is, then move the projected explosion point by a random amount and repeat the check.
Messy and laggy.
What is this for? Assuming it's a cutscene it's probably easier just to fake it and make the loons invincible with an eventhandler hit and a setdammage 0 loop.