I agree - commending the dude for making the video effectively denouncing his own actions. I've seen the clip many times over the years, but had not seen his release of it - honestly have watched a lot of his stuff and feel stupid that I didn't realize that was him!!
As an instructor, I have advised folks against the Serpa holsters, and other index finger released retention holsters, for this very reason. It develops the habit of pressing the index finger into the trigger guard during the draw. It's one thing to instruct students to hold their index finger along the side of the pistol, but it's another to teach them to PRESS their finger against the frame, and certainly yet another still to utilize a holster which requires that pressure. Many types of competitions, and many shooting ranges and clubs prohibit Serpa holsters for that very reason.
I've never seen the correlation between the thumbdrive holsters and involuntary deactivation of a manual safety, but I'm not certain I would personally care. I train to find the safety with my thumb, and deactivate the safety as the muzzle comes to level. If I accidentally switched off during my initial holster clearing upward draw, it's not functionally any different for me. Not ideal, but not a dangerous condition yet, in my opinion.