Serpa was definitely the problem here and no manual safety on the plastic wonder 9 and never carry with one in the chamber because you'll definitely have time to rack the slide plus the sound it makes has a good chance of scaring the bad guy off and don't carry appendix you'll shoot your dick off and the p320 is totally safe now because sig pinky promises
No need to protect yourself in court if you're dead because you carry your 1911 hammer down or unchambered and got domed while trying to manipulate your firearm.
I don't know what backwater LE, mil, or body guard program you learned that in but it's gutter-tier advice for private citizens.
This is a really neat toy, but the points he tries to make in the video are pure cope. Nobody is going to protect the VIP with 22lr.
The B&T TP9 maybe has some merit in this cheek pistol format but I really don't see any real an advantage when compared to a full-size 9mm pistol concealed on the waistband.
Sig Mechanics on YouTube has some great videos about the internal mechanisms of the P320. This video specifically covers the pre/post "voluntary upgrade" changes.