Since we see more female Viera outside their forests during quests (the one in the relic questline comes to mind) I certainly am positive that the writers might be able to come up with a logical reason for male Viera leaving their homeland easily. Even if we see just a few of them, just like with male Miqo'te who are pictured pretty rare compared to female Miqo'te. Let's hope we get some information about the missing genders by the end of the year.