I call bull!@#$. It directly conflicts with the letter you already sent the League... And Silnaria isn't trging to pick a fight. Merlin isn't THAT stupid. I almost ordered a hit on Ottar for the sheer outrageousness of the entire thing.
Ban him and be done with it. If he stays in Tara there is exactly one logical conclusion: Ottar bribed/cajoled/otherwise convinced Josep to do it.