I'm pages behind but the one thing that comes to mind that TS felt was necessary to "pre-splain' (love that term) was the
"only" key to the gate that she claimed Gannon was in possession of. I wonder if this piece of info was corroborated by AS, that Gannon had the
only key. Did AS notice the key was missing and question her about it? Was she in possession of the key and not Gannon and she lost it? I could see the searchers sifting for a key, or as
@GordianKnot suggested perhaps a sim card? I'm leaning toward that illusive KEY only because TS found it important to bring to our attention. I really have no definite reasoning for this other than the key is in fact missing along with Gannon.