People's public personas really aren't a guarantee that they'll act a certain way on their property, especially when they are not doing something voluntarily.
Combine that with the fact being that gun ownership is a Constitutional right--that means the chance that anyone can have a gun is above 0. And various attributes of anyone that might determine whether or not someone is about to retaliate are extremely unknowable without long observation times. There's no possible way to quickly ascertain someone's proclivity to violence, agitation level, emotional state, number of guns they really have on hand, willingness to use them, etc. People will act differently outside of a public setting like work, on a TV show, etc.
So as long as guns are as easily available as they are currently, it's not unreasonable to expect a law officer to start the interaction in this way which is a manner that protects the officer the most.