In the Mythos blogpost they revealed to run the model like a 1000 times on the same code-base maybe with slightly different prompt or temperature. That suggests it will just be pay to win. If the 'attacker' spends more money/tokens than the 'defender' you will eventually be outclassed.
It's even worse, it's loot box style. Not pay to win, but pay to have the chance to win. The result will always be non-deterministic, so for some cases it can give you what you're looking for from the first time, or it can take 1000 tries.
I agree the cost curve has shifted. But if we take the Mozilla team's Mythos report as a broad baseline, you need to hire something like 10 security engineers to equal the Mythos productivity. Put another way, everyone's under hiring security by a LOT right now, we just have been lucky enough to see similar under hiring on hackers.