You speak truth. People will be “flinchy” at the oddest times for the oddest reasons. I’ve seen guys bigger than me get flinchy when shooting the M4… why? It has almost no recoil at all. It’s 99% mental.
My lovely wife had never handled a handgun in her life, ever. I took her shooting and, because she had no bad habits to unlearn, she learned just fine. Being “flinchy” can be overcome with training and incremental increases in power. Even though my wife is only 5’6″ and 120 lbs, she can handle a 1911A1 with no problems…
I started her off with a simple .22 pistol. Piff, piff, piff… Then moved her up to a 38 Spl. revolver. Bang, bang, bang… let her play with that for some time. Then another increase in power – this time I put 357’s in the revolver she had been using (it was chambered for 357’s… no worries) and let her play with that. Then came the big 45’s. She ended up shooting up 3 boxes of my (expensive) 45 Colt ammo using that big Colt’s revolver I have… at that point, I told her that if she was going to shoot up all my ammo, then she rated her own handgun and could feed it herself.. she settled on a 357 revolver – a hot-rodded S&W 686.
Recoil can be mastered with time and proper training for all but the smallest and/or most frail… the worst thing you can do is hand a noob shooter a very powerful handgun and let them touch rounds off when they don’t know what they’re doing or what to expect… that’s where being “flinchy” comes from.
The wicked flee when none pursueth..." - Proverbs 28:1