He waves his hands emphatically, which is a contrast to the almost feral way his double crouches ready to run. (Well, Izuku never denied he too takes part in a little feralness...)

"Stealing my body is not minding your own business! What were you even doing out after hours anyway?"

He's less apprehensive now. Himiko could copy people's Quirks, but there is no hint of One For All here. Even its Danger Sense is quiet. This person really does just want to get away. Izuku should be more upset about his likeness running around, but he's more concerned with keeping others safe.