Almost no-one decides they'll just drive instead of flying because their plane was delayed. After the first crash, Boeing certainly knew that it had hooked up

Almost no-one decides they'll just drive instead of flying because their plane was delayed. After the first crash, Boeing certainly knew that it had hooked up MCAS to a single AoA vane. I don't think they could sincerely argue that hooking up a single sensor to a primary control surface with no backup sensor is airworthy -- either practically or legally. There are regulations about it, and that's why Airbus has three AoA vanes and uses majority quorum. That's why I think the grounding should have happened earlier.