It’s quite a gamble when she’s approaching him with that spade and talking out of her head.
My guess is the officer is not obligated to gamble when he’s on duty even in Vegas.
Gamble with what? No one in the video is in any danger of being harmed. The only "risk" is that she will keep wandering around carrying a shovel, babbling incoherently, ignoring the cop's commands.
She is probably drunk or schizophrenic. Those are not capital crimes. There is absolutely no need to shoot her.
If that cop can't physically grab the shovel away from her, he doesn't deserve to be in uniform. It will take her a few seconds to prepare to swing. Any adult male in decent shape could get close enough in those seconds to grab the shovel. I could do it.