Do people honestly think Biles just got nervous? She lost the ability to track her time and space while flipping through the air at however fast she's going. If a QB got something similar, an inability to track distance/speed/depth-perception/etc... yeah they are dumb as f*** if they go out on the field. Likely to hurt themselves or others. Let alone be able to judge pass routes and shit. It would be a trainwreck.
And I think it's important to note, it's not just any ol' QB. The QB in question would need to be the most decorated QB of all-time. Like Tom Brady. Because Simone Biles is the Tom Brady of gymnastics. If Tom Brady, after winning 6 Super Bowls said "It's a bad idea I play in this big game." And then won ANOTHER Super Bowl years later... that's the equivalent.
Like how much more would Tom Brady need to accomplish for us to trust him that he might know when he's good to go and when he's not?