Seems like you broke the rules and deserved the punishment, which is up to the staff member's discretion on what to issue. A warning and a ban is standard and in this case, well deserved.
You not only prop blocked SCP-035's cage which is already blocked by physical map properties to simulate a cage which is what it is, but you also went afk. This prevented people from getting to you, which walled you off from other players. Thus you broke the rules and got punished. The mind-numbing thing is that you don't seem to understand the reason why you were banned which is extremely amusing to me as you try and rationalize what you did as not breaking any rules.