I have a problem with Hogan's Alley

I really enjoy these old Zapper games, but for some reason the innocent professor always gets my trigger finger itchy. I cap is ass almost every round. I realized that I could train myself to more closely analyze the situation, then act more appropriately, but then I thought, "What would this guy do if every time he stepped off campus, he caught an acute case of lead poisoning?"

He'd make a sign. And so he did:
https://www.dropbox.com/s/bfp3akipqg7ovh0/Hogan%27s%20Alley%20-%20Don%27t%20Shoot%20the%20Professor.nes?dl=0