You cant stop him, for sure he is not a Stake agent as he is just a player who feel unsatisfied with what he get in Bitsler then he compare it to what he get in other site.
He thinks that he can get all the same in all sites, he does not understand that every single site has their own policy to give bonus.
Perhaps he will also attack other casinos in the near future if he play in other casinos but he does not receive as what he get in one specific site.