He does trust them to fight back. Strange even wrangled a 'dude, please just murder me if I get brainwashed again' promise out of Lambert. But it's the simple fact that he might get enthralled and hurt people again that Strange is terrified of happening. He's also aware of the fact that Portland him was really, really lucky there was a convenient mission that the Rose Queen wanted her lackey and her lackey's lackey to take care of. Otherwise who knows how long he'd be stuck in Nightshade's realm.

Still, Yuya talking about how they're going to fight back brings up a different point. "Others might not let me walk all over them. You're going to help protect people," he gently bosses. "The carnival's rubbish at defensive magic and if a High Fae shows up, they'll need all the help they can get."