I'm not sure how I feel about this. On the one hand, it seems sort of mean-spirited to me, like hate-drafting. Only instead of grabbing a card that you're not going to use, you try to pass it off on someone else who you don't think will use it as well. So it's sort of insulting to one player and spiteful towards another.
But on the other hand, I don't really see any point to having a rule against it. I think we're all smart enough to realize if someone is trying to trick us. And if the point is simply to expose someone's plan, then each person is going to have to weigh the merits of handicapping their own decks for the purpose of damaging someone else's.
In short, I'd say that if you don't want someone to get a card, the best choice is to take it yourself.