I read a lot of commotion, but I don't have a problem with this.
Even if you have to pay to enter the compo and can win money with it, I still don't have a problem if he posts about it here. Its up to you to decide if you want to enter it and pay for the entrance fee.
Its not that this is illegal, cus it isn't. We don't have rules preventing him from doing this either. If you disagree on paying money to enter this, simply don't enter the competition.
If you however would like to join this without paying, perhaps you should organize your own competition and see what happens.