I'm starting to have second thoughts on this. As I said in my first part, this reminds me of Diddy's infinites. Unlike Diddy's infinites, this setup breaks your shield. Even then I thought, "so what? We still have to catch key, which is a big pain...."
Then I thought about the current stage list. In most places, the starter list is FD, SV, BF, T&C, and DL64. The Key recatch is trivial on 3/5 of these stages, meaning that we can always force the opponent to an easy recatch stage at least twice. IE we strike SV and T&C, we go to one of FD, DL64, or BF. Let's say we win game 1 on FD. They take us to some CP and win. They ban DL64, and due to Dave's stupid rule we can't pick FD again. So we go with BF.
Like I said, we are guaranteed two trivial recatch stages for a Bo3. This is honestly worth practicing because risk : reward is so heavily in Pac-Man's favor, and we are guaranteed 2 easy stages to get the key.
Even if you can't do the full infinite, I'm sure zdrop Key -> footstool recatch -> zdrop again + drop hydrant => 52% pretty easily, and you still have the key available. I'm eating my words. I'm going to try to abuse this as much as possible.