My friend got permanently banned

Hi there, my friend got permanently banned. My friend primary account is Immortal and smurfed in Plat 2 to play with friends. He got permanently banned with Cheater Detected, one of my friend in the same lobby got account locked until 6 months later. Is it possible to have Cheater Detected with smurfing? As you can see previous TenZ is Radiant, and smurfed in Plat lobby without any detected.