It doesn't imply the only way to be safe is a to have a safety on the handgun. It's not the "only" way.
But it does expose the scenario where the safest gun handler in the world can have some inept cop shoot them in the leg because that inept cop doesn't "keep their booger picker off the bang switch". The odds are that having a safety would have prevented Fumble Fingers the DEI Hire from shooting him.
except when carrying having a safety in defeats the purpose of self defense. A soldier in combat does not carry with the safety on.
As I mentioned earlier in the Tueller Drill.