Dean's used to protecting the weak, as cliched as that sounds. So when Chaucer shuffles over to him, Dean situates himself a bit in front of the guy, but doesn't make a move to take the gun.

Looking up at the others, he assumes a non-threatening stance.

"All right, so obviously threatening people doesn't work. Let's try using our nice words, yeah?" Dean says politely. And then he looks at Chaucer. "Don't shoot anybody, alright?"