With Michael's movements, Ern's second-in-command darted towards the door and intercepted the interferer with a binding spell and a silencing spell in quick succession and with a couple more flicks of his wand down the the hallway, where one of the more junior members of the team followed up to supervise.
"Can't you see? Your carlessness--anyone's carelessness can kill us all. If she actually cared about you--or even herself--she wouldn't want you in this room since you may very well get in the way and cause some or all of us to die." He didn't know whether he had to spell it out further, but he said what needed to be said. "I actually have no fucking clue as to why I haven't sent you back to the Ministry yet since you're drawing attention to yourself in a situation where lives are at stake. This is not a fucking game or time to worry about your fucking ego and being some fucking hero. Just let me do my job."
He knew that letting Michael stay in the first place was a severe error in his own judgement, and he wasn't going to hear the end of it--ever. This was the sort of error that could result in really bad stuff happening, and he was starting to feel the stress of the situation.