I agree with you. Training is key. But that particular switch design leaves too much room for operator error. Of course, this is just MHO (based on 45 years of shooting causally and competitively - rifle, shotgun and handgun).
I wonder how many more "operator failures" are out there, using this type of light setup??? My guess is - more than just this one Plano incident...........
Here's an interesting experiment - hold out your right hand and twitch your middle finger closed. It's virtually impossible to do without some sympathetic action to the trigger finger.