737 Driver and others
The problem with that line of reasoning is that MCAS doesn’t activate with flaps extended. If the Capt was that concerned about MCAS, all he needed to do was leave any amount of flaps out and deal with the AOA failure/Airspeed Unreliable NNC.
When I tried to get into the psychology of those fearful moments, I postulated imagery flashing into the mind of the ET PF of this new system he'd learned about. Yes, the flaps would have been a godsend. He could even have subconsciously sought the comfort of automatic flight while he tried to get those chaotic thoughts into some sort of order, so I wouldn't be surprised if a major aid was simply a blanc.
The main point of my comment was the shock factor being made worse by knowing about the first crash - the sheer sense of unreality could well cause gaps in an almost nightmarish recollection of the news.