He may be extraordinarily protective and quick to overreact (although try telling him that), but he can be reasonable. He's a pragmatic man, and though he has a temper at times, he doesn't let his emotions control him. Otherwise, he wouldn't function well at all in his job. He's come close, often, to wanting to physically hurt a suspect and though he's certainly yelled plenty of times, he's rarely committed any serious infractions when detaining even the worst suspects.

This conversation between them is tame, and Kurt knows it. He's also fully aware that Anders and Sarah might only ever just be friends, nothing more. But the point had to be made clear nonetheless. Anders has reacted well to what was his thinly veiled warning, and he appreciates that.

"Good," is all he says in response. They can be friendly, he even has a good feeling about the guy. He just had to make that point. "Then you can keep leading the way."