Guards had no knowledge of his rebelling outside of the message in chat and its something they might've legitimately missed. As soon as the guards found the guy he was immediately killed. I do not see any malicious intent here.
Secondly, I have no context on the snowy situation. Was snowy MFKING/doing something that was teamkill worthy? Was it retaliation? Was it Accidental? Was it intentional? Nothing in the clip points towards any context. If theres a longer clip of the teamkill please post it here.