I don't know yet if I guessed correctly, but I'd say that the infinimuter and the Half-Dragon exploit were both fixed by vanilla game updates.
(I'm not sure if infinimuter still works but I noticed that the Fire Heart doesn't charge when you use Lemisee which I believe wasn't implemented in the early versions)
So if I guess right, I still think it would make sense to extend the Half-Dragon fix (which is that a Half-Dragon canhitting a magical immune plant twice kills it) by adding something to prevent the player attack to go zero (and still, you don't even need that in the EE thanks to the Ensnare trait) or saying that if you do zero damage to a plant twice you kill it.
Anyway, congrats one finding that exploit, whatever it is (I still haven't watched the run).
By the way, your remark about GoatPerson + Fido was very interesting, it never occurred to me. Did you test if it worked? I still believe that Shadow Heart is the best item around for GoatPerson , because you will still worship gods with it.