Multiple people he has to protect, there at a disadvantage, also forget about the POISON on the arrows? He makes ONE mistake, someone dies. So for now he has to play nice. Remember they don't know his "familiar" isn't an Owl but a "Half Vampire" so he still has a CARD to play. Right now the Villain is BEING arrogant, which works to his advantage. He has NO reason to believe he'll keep his word, after all, he allowed them to walk into "enemy territory" that didn't DECLARE themselves enemies, and of course the fact he made the decision WITHOUT the other chiefs means this is a COUP on his part. So he's acting ALONE with only his loyalists. But He acted Dishonorably by not declaring being on the side of the demons, and even if they made the deal, MC and co should have been made aware of it, there's a reason you DECLARE your intentions, sneak attacking ENEMIES like this may work out well short term, but long term, it makes you untrustworthy because "Sacred Hospitality has been violated" got to ask yourself if GAINING a bad reputation long term for a short term edge is worth it! (Just look at the Red Wedding, it wrecked HAVOC on the Frays, Boltons and Lannisters reputations after the fact, yeah they CRIPPLED the Stark forces and KILLED Robb Stark. But it ensured NO ONE will trust them AGAIN, Frays especially as they got HUNTED down by Stark Holdouts, AND assured the Boltons despite CLAIMING Wardenship of the North would ALWAYS be seen as the dogshit POS they always were, not helped by Ramsey continuing to ANTAGONISE when Roose knew he and his house were in a FRAGILE situation and Ramsey would be the NAIL that causes FULL ON Civil War, not that Ramsey cared too high on his Perceived INVINCIBILITY to notice! And of course FURTHER destroying the Lannisters that all SIR BALDY had to do was KILL Kevin to assure Cersei had NO ONE to reign her in and she can 100% destroy all good will the Lannisters had left! So yeah "don't fuck with Sacred Hospitality!) and so MC has no reason to believe he'd keep his word, only thing keeping him from unleashing is he has hostages, but the second their secured, well he has no reason to HOLD BACK.
Sorry MC isn't an Edgelord who doesn't care about causalities (I mean, EVEN THE EDGELORD MCs out there would make the same call as he did if they had no means to protect others, again even if he can HEAL the damage, they were using POISON, something I don't think he can deal with his healing. And it works in his favor since THEY have no idea of the CARDS he has to still play, or that he can be CONTAINED! NEVER stop the enemy when their "defeating themselves under the BELIEF they THINK they are defeating YOU!"
