Bannd for to many kicks

Hey ,first sorry for my English but I have a question :
I played with my friend on our server (we are admins) and then I kicked him for using a M320 .

But form this point he wasn't able to join any server ....

So he told me about a rule that if you have too many kicks in a short time you will be banned from the game.

First is it like this and if yes what now to do ?

Thx, for your answers ... :D