if I play a Behold The White Bull
Shootout Tau Technique, Boot: Increase the casualties of both posses this round by this dude's influence. Your opponent may send all dudes in their posse home booted. If they do, this dude permanently gets +2 control points and unboots.
and my opponent has a dude in his posse with a Yagn's Mechanical Skeleton Equipped
Opposing cards cannot boot or move this dude.
since it is my card effect that is giving them the choice to move home, can they choose it?
could they elect to go home and everyone but the Yagn's dude leaves?
would some opposing dudes fleeing qualify for the +2 CP? or would it need to be all of them?
(I did ponder a world in which you run Behold the White Bull under Full Moon Brotherhood stopping the opponent from running, but that is too hypothetical, even for me)