You missed a big step in that “impossible” cockpit environment: flipping the runaway stab trim switch. It’s an emergency procedure that pilots should be ready for at any moment and would stop MCAS from the ability to trim further. And in the Boeing system, once you flip it off you NEVER turn it back on.
All the design changes were not great, single AoA sensor not great, but that’s a critical response you train to do in less than 3 seconds. Nope, it wasn’t in an extended manual T.O., still a foul, but I understand why they thought the corrective action could be done in 3 seconds. Because it’s the same corrective action already trained to for runaway stab trim.