My account banned

My account was banned for playing with a person using a cheat. Right now, I remembered that I went into the arcadia zombie mod room, where there was a person using third-party software, but immediately left the room. He made it so that I had increased damage and I killed zombies from one place, but I was not on the team with him. Why were sanctions applied to me, because I did not play with a cheater, but simply entered the room and immediately left? Why was my account banned? Where's the justice?