Woah. You know that whole debate about farming (points at Kong), if we set a minimum upped card amount, it would cut down on that a lot. Most lower levels aren't going to have upped rushes, and any upgrades they do have, are probably going to be put into things like instosis and poisondials. Not exactly fast, farming decks. It would discourage the noobs from doing it.
It would also stop noobs who are "sharing the wealth" (they just got farms, want to pass it on), because they won't have upgraded rares or towers, meaning that they need to invest 9k just to make their farm effective.
As to the OP, I don't really see a lot of noobs playing it except for when theres a farm going on, or if somebody just accidentally clicks it/just checking it out to see what it is. If we really want to ban noobs from pvp2, this seems like a great idea.