She's bee around for quite a while actually. I believe the first time we saw her was at the war council discussing the "party platter" and Ansom's response.
She's been used fairly consistently in fact as the "questioner" of his plans, giving him the opportunity to explain his thinking to her (and the readers) without seemingly pointless exposition. While we don't know how "inconseqential" she has been to the RCC's strategy, as a narrative tool she certainly served a purpose to the story. Now that that part of the story is ended though I do not that purpose continuing, so no valid reason narrative for her being brought back. If Darth Unsom requires such a sounding board in the future, we have Parson to serve that role.