It doesn't tell her much; she already had them down, mentally, as highly dangerous by use of magic. This is going to have to be a very fast maneuver.

She nods, curt and obedient. Very obedient. This is a lot simpler than her plan of "open up, the other guard's back and you should see her so you don't fry her accidentally." And she stays in the doorway as soon as Emma steps out. Nothing's going to get by her.

Until she's busy with other things, but by that point Emma's priorities will be readjusted.