[Bucky remains impassive, despite her scowling. He's honestly just trying to give a bit of good advice - to help her and "Ian" both. He knows better than anyone what it's like to feel startled and threatened, to not be able to control your instincts. And he knows what his other self can do. It wasn't that long ago that he threw a teenager into a bookcase for throwing a lamp at him.]

I would advise no sudden movements. Sometimes it's hard to separate threat from benign. Hell, a person shakes my shoulder to wake me up and they end up in a chokehold.