what was the gas station clerk.........

That's all he had for a weapon. He wanted to scare the perp so the cop could shoot him.

It was either bad writing, or just a dumb-ass move, maybe showing a bit of dark humor. Even dumber was when Witt stood outside the gas station, glaring into the dark, knowing baddies were hot on his tail. They can easily see him, but he can't see them. He's lucky he only got shot in the leg. Even Dot made a few dumb decisions in this episode.