"Look, I know you're the law." There might have been a hint of Stallone in that from a particular movie, but not much. Dean knew this wasn't the best time to joke, seeing as he was turning down something he'd started in the first place.
"It's probably best you stay out of it. Don't want people involved who shouldn't be. Let's leave it to the vigilantes and wrongly accused, okay?" He wasn't being a martyr exactly, but he didn't want to take an already hurt person into battle. As if that really ever stopped him, Sam, or Bobby.