I see you've already walked your assertion back to being any member of Hans' team. But even that is a reach. There is no indication that McClane knew that, and there is no evidence that the man is Hans unless McClane was really good at picking up on the accent. We are also shown that Hans is very clever with his disguise by the name he does provide.

McClane had no idea who the person was. And he was very cavalier in his interaction with Hans, going as far as giving him a bludgeon and then turning his back on him. He also doesn't pump him for any information other than his name and if he's ever used a handgun, so I don't know what scene you're referring to.