We don't know, which is why they are free to make up his backstory.
So they shouldn't make Sulu gay unless he has a major storyline that revolves around him being gay? Or they shouldn't make anybody gay because people will "buzz" about it? What are you advocating?
It doesn't have to be Kirk, McCoy, or Scotty to still constitute a significant choice, as is clear by the strong reactions within the fandom. And XIV is already confirmed; for all we know they may expand on Sulu's family in the future. .