We don’t know (and Mueller doesn’t know) what she may know.
I’m not expecting much, but when a key actor/witness in the saga dismisses the dossier as “absolute nonsense” AND she is Russian and (possibly) very well connected in Moscow, why the heck would we not want to know all that she knows that is relevant?
You are still only focused on why she wants to stay away from the USA, and not upon whether she has any information that could prove useful. I would like to know why SHE dismisses the dossier as “absolute nonsense” — that is quite interesting, coming from one of the ppl involved in this story. Does she know anything about the process, the origins, about FusionGPS, etc. that would inform her contempt for the dossier?