Okay, granted, these ladies didn't have a whole lot of context for the situation, but Tony really didn't think he'd have to spell out his intent to the whole party. They go, he takes Loki into some manner of custody, willing or not. He was not letting the Patron Saint of Stepping On Lost Screws just wander on through Illinois, zombie plague or no. It was bad enough he got this far, causing fuck knew what kind of chaos in his wake. No one needed to deal with that right now.
Only when Kate loosed her arrow Tony only got as far as an admonishing, "Jesus, shit," as the woman tumbled forward and forced the arrow through the back of her brittle skull, and then all hell broke loose. That was a human being, wasn't Kate supposed to be a Young Avenger? And, okay, Tony never expected to have to pick sides between a horde of completely unscrupulous cannibals and a guy who thought a can of actual, real snakes was a pile of laughs, but Tony was picking the cannibals here. They hadn't actually done anything to him. Personally.
Suddenly, Iron Man was between Loki and the writhing edge of the forest, palms up and glowing ready, hovering just over the ground and throwing dust up with his jets. "Stop killing your faithful servants and we have a deal," he snapped, thinking they could at least agree on that. Without anyone left to mess with, what would Loki's life be? He'd have to take up drinking, like a normal person.