Personally, I think it’s likely that Matsuno has a veto against anyone making male Viera that I think Yoshi might be inclined to support, and we already know that apparently nearly all of Japan think male bunnies are “weird”.
Yoshi also said to look to the Ivalice lore for info on male Viera, and the lore in FFXIV RtI states that male Viera are so rare and reclusive they’ve basically never been seen by non-Viera.
So while genderlocking was a ‘mistake’ for Roes and Miqote, I think they might regard the Viera lore as superseding that…