The solution is to fix what is CAUSING the problem, not try to stop people from doing it.
The problem is that people sometimes DON'T WANT cards, especially in nuclear games where cards (which are completely random) can hurt you. In these cases, there should be an Option to DISCARD unwanted cards. If this were possible, no one would let time run out anymore because they would have an easier solution to their problem (which is they don't want to have to use the cards they have).
I mean, how stupid is it to have a rule that a player has to do something that will hurt their chances of winning? No one is going to want to follow that rule, they are going to find ways around it. So if your rule is that players have to nuke 3 of their own territories just because they happened to RANDOMLY get those 3 cards, then they are going to find a way around that. The best way to "fix" it is to not make them do that. Again, put an option where they can throw out the cards rather than play them. How is that hurting anyone else? Player A got 3 turns worth of spoils and doesn't want to use any of them, why can't he just throw them away and try to get other cards, why does he HAVE to use them? How is that giving him any type of advantage over another player? He's not able to use the cards he has, isn't that a fair trade off - he doesn't nuke his own territory, but he also doesn't get to use his spoils at all - seems fair.