Primarily because of the ownership over the Big West 41, and the really questionable claims that HGUSA was making in the lawsuit. Asserting copyright ownership is one thing, but some of those claims were deeply suspect under scenes a faire law. It potentially showed questionable judgement in the maintaining of the copyright, plus the fact that what they were suing over was (at least in Japanese courts, and legally acknowledged in US courts) never something Tatsunoko owned in the first place. I was hoping for an update on the whole thing from Leonard French; he'd done one video on the situation and was following it but the settlement (and its private terms) happened before he could follow up on things.
The big thing was not so much the Battletech lawsuit, but the very related arbitration that happened concurrently that nuked their ownership of the characters and mecha; they have legal access to the X hours of anime that exist but that's it - anything new requires new art designs.
Reasons they'd stick WITH HGUSA is, of course, 30 years of active relationship, plus the 8 or 9 figure film deal being kicked around. Which is still on in a big way apparently, and is something I'm immensely curious about come the Great Transition panel at SDCC. Which I suspect, as stated before, is likely a reboot announcement.
