I'm not buying either of these theories, he's a tyrant, the first thing he'd get in order is his own harem, whether they are goblin, human or elf, his strength is reliant on keeping a constant supply of fresh, loyal troops coming forth (even if they weren't being bred by him specifically they would still be in the breeding chambers for his top warriors to use), any outlying tribes under his dominion would only get to keep their females once his harem was full. The only explanation I can think of for there being no females about is that he didn't want the competition.
There is another theory I got after thinking about it.
He was an old Goblin and probably only King in name, the war (Nergals) did cost him most of his subjects and like mentioned before includeing his women (they are considered the strongest Warriors among the Goblins).
When we attacked his stronghold there were only few Goblins and Trolls which he had lured into his tribe to bolster his ranks and avoid a rebellion, the other tribes still prepared for one as the Pigmy attack proved shortly after we dispatched the old Kings last men.
Without any other tribe listening to his commands they kept their females to breed their own numbers and prepare for their uprising, only the green Goblins remained halfway loyal to him and Shakalah was their only female.
what is the percentage for shakala to birth a girl ?
Without the Patch from the OP 0% afterwards quiet high and growing each time it didn't succeed
Well,Black Goblins are the near we get to hobgoblins in this game,since they are bigger and stronger than the average goblins,and will probably result on more content for your raids
they also rule in the mountains and have access to iron lores and mines, which addsup with the promisses of forges in our stronghold