Talking to Dad this morning and he mentioned that the original case had settled a couple years back, and that a few other positives have come about since. It appears I didn't do any followup so here's a quick revisit in the interest of closure and complete info.
TLDR version: The BLM figured out they were about to get their poop forcefully reinserted so they "settled" (attorney-spin for the BLM giving up and slinking away like the rotten, petty, yellow cowards they are). Boundaries reverted to pre-redraw locations and boundary criteria clarified. Later, a Texas attempt at making sure the BLM used third-party surveyors rather than their own internal crews as a way to ensure objectivity. More recently, a ruling mandated that fed access to the properties was strictly limited, requiring landholder pre-notification and adherence to a designated route. I see some references to a more structured and independently-managed survey program currently in progress, but didn't follow the rabbit hole.
The 2017 settlement.
https://www.texastribune.org/2017/11/08/texas-red-river-land-lawsuit-ends-settlement/More recent update on proposed restrictions greatly limiting the BLM's surveying authorities, including a requirement for surveys to be done by disinterested third parties.
https://www.timesrecordnews.com/story/news/local/2019/02/09/measure-protects-landowners-embroiled-red-river-boundary-clash/2825255002/Late 2019 ruling which puts strict limits on fed access to private land along the Red River. (i.e. no more of this "go wherever, whenever, just because we can" business)
https://texasfarmbureau.org/judge-allow-federal-access-private-property-along-red-river/Brad