http://www.alderac.com/forum/viewtopic.php?f=375&t=115366&p=1489555&hilit=shooter+guard#p1489555 I sight this ruling because it clearly says two things. First, Shooters remain shooters until the end of the shootout round, even if they leave the posse. In this case, the dude cannot get control points while they are not in the posse, they get the control points if they reenter the posse.
“Shootout abilities can also only affect dudes or their attached cards if they are in a posse, unless that ability would bring a card into a posse.” -Slinging lead. Step 1.
If a dude is a shooter in a posse affected by Heartseeker that losses the round of the shootout, and is not in the posse when the winner is determened, they cannot be aced by Heartseeker, because;
“Shootout abilities can also only affect dudes or their attached cards if they are in a posse, unless that ability would bring a card into a posse.”
(I am not on the rules team, this is my interpretation of a very clear rule)
It is nothing to do with prevention. It cannot happen. It cannot happen because the the dude is not in the shootout. If the shooter is discarded, they will not be pulled from the discard pile and aced, because they are not in the shootout. Leaving the shootout is not a direct violation of Heartseekers prevention clause since the affect can only be determined after the winner is determined.
If it is ruled that heartseeker cannot be prevented even by the rules explicitly hard wording; If the shooter is in the discard pile (they are still the shooter until a new shooter is selected) will they be pulled from the discard pile and aced?