The flaw in your is you are looking at when the ball was snapped, not the point when a decision had to be made. That’s not real world. In the real world, and in real time, the play clock is ticking and about to expire, coaches are yelling, and Garrett has to be sure an official can hear the timeout early enough to get the timeout called ....
You act like he could have calmed his coaches down, and asked them them to all take a second look while he joins them in deliberately perusing the field, checking every player closely to see all were set, then if someone wasn’t set he could calmly seek out the nearest official and politely stroll over and request a timeout.
This isn’t T-Ball with the coaches setting the ball on the tee, and the batter having time to step into the batter’s box, peruse the field to see how the defense is lined up, take his time to get comfortable, then swing. In the real world it’s a split second decision with a 95 mph fastball on its way.
You, on the other hand, can go back on video, knowing in advance what you are looking for, watch up until the exact moment the ball is snapped without worrying about whether there is time to find an official and call time out if needed, and if you aren’t sure about something you can rewind and look again.
And, the point you keep avoiding like the plague is there was no statistical reason a timeout would cause harm even if it was ultimately decided the players had got set, but there was harm if they hadn’t got set and he did not call timeout. So, the choice at the time was no harm in calling a timeout, and potential harm if they didn’t.