There's probably more opinion in that than fact, but the real issue--since a U.S. court ruling in 2003--is that Harmony Gold's claims to Macross doesn't extend beyond that of the original SDF Macross
series (in the U.S. only). Big West can release or sell the rights to other Macross shows in the U.S. whenever they want. So that aspect is up to Big West, not Harmony Gold.
Where it gets truly ugly is in regards to the licensing and merchandising rights to the original SDF Macross
series in the U.S., which Harmony Gold acquired from Tatsunoko (which acquired them from Big West).
As far as any rights dispute with Warner Bros., that's easily resolved by not using the exact same mecha and character designs from the original SDF Macross
series, which they likely wouldn't for a live-action movie anyway.