in team games that player can still contribute to their teams deployment
A fair point which has been raised already, but not a deal breaker in my mind. Would you routinely allow one of your teammates to get into a spot like this?
Also, this isn't a reason not to implement the suggestion, it's just a reason why gameplay would be different as a result of this change. Of course, if the OP was not intending to change gameplay, then this is a reason not to implement this suggestion from that point of view.
The points in a terminator game would be handled just as they are now in any map with a losing condition: the player whose action triggered the elimination would get the points. So, instead of the points going to the player who took Alcatraz away from the stuck player, they would go to the player who took away the stuck player's second-last territory. Not much of a difference.
What happens if, in nuclear spoils, the player causes himself to get locked on Alcatraz because of a forced spoils cash? Do the points go to the gamewinner?