Did you even read what you wrote?

"The cop wasn't detaining the old man by slamming him on the ground. "

In order for the law enforcement officer to do that, they need a warrant or in absence of a warrant they need a probable cause.

"Do you want the cop to go get a probable cause warrant before they take any action to defend themselves?"

A warrant and a probable cause are to different things.

"I think we are missing something here."

I agree

"I am just about done repeating the same thing again and again."

It's up to you. ;)