Unfortunately the 2A community is filled with fud and hollywood-esque beliefs. Those who have little training or practical experience often fall victim to believing these fantastical "what-if" scenarios.
The amount of times a firearm has been taken out of someone's duty holster and used against them is a statistical rounding error. Most LEO departments require Level 3 Retention holsters, making this scenario nearly an impossibility. Additionally, a safety isn't going to save someone's life if the "bad guy" has wrestled control of the firearm away from the owner.
This entire scenario is fiction. Manual safeties often do more harm than good - which is why just about all modern handguns have no manual safety (outside of the few States which, out of ignorance, require them by law).
> and someone tries to get your weapon off of you and succeeds, a manual safety could save your life.
This is something straight out of a movie...