If Gorons don't sexually reproduce, then they don't have a gender and thus can't be gay. Gender is the word used to define members of the same species with biological differences necessary to facilitate reproduction. Something that reproduces without copulation is either genderless (asexual) or hermaphroditic (possesses both 'male' and 'female' parts and can self-fertilize).
As to the Gerudo, though it's true that one male is born every hundred years, we are also never told a baseline life expectancy of the average Gerudo male. I've made my thoughts on this known before but I'll reiterate some of them here. Ganondorf has displayed a startling longevity, possibly much longer than the average Hylian male. From Hylian culture prevalent in all the games, it would seem that they are analogous to humans so we can assume that their lifespans roughy equate to our own. However, if only one Gerudo male is born every hundred years and assuming they reproduce sexually like a human or Hylian, then it would stand to reason that the one male must indeed survive this long and also still be sexually active. This means that a centenarian Gerudo male is not considered elderly because he is still virile. This can be assumed because obviously, to birth another male at that hundred year mark would require sexual reproduction.*
In fact, one could go a step further and say that Ganondorf is actually a traitor to his people. In order to sustain a certain population, he would have to be producing children with a significant percentage of the existing female populace. This would be to ensure a diverse enough gene pool as to avoid inbreeding and defects. However as we know, women have ovular cycles and just casual sex would not be enough to support population growth needed for survival. Not only would he need to produce significant numbers of offspring, but if his monologue from Wind Waker is to be believed, the Gerudo suffer form a high mortality rate thanks the their native climate. This means it would essentially be his duty, almost like some reverse Queen Ant, to do almost nothing but copulate for a significant portion of his life. By pursuing nothing but his ambitions of holding the complete triforce, he's actually guilty of dereliction of duty in a manner of speaking.
So why is it then, that when faced with a job like "have non-stop sex with only the most genetically fit members of your race", he chooses something else? Could Ganondorf in fact be gay? Honestly, I wasn't going to this conclusion on purpose despite the thread. I originally only intended that one thing about the gorons, but the more i thought about the Gerudo, the further along this line of logic i progressed. In fact, until just now i was about to derail slightly to something completely different about Ganondorf and his apparently specialized testes… But really yeah. He might just be gay or at least asexual (in the more modern, "i am just not attracted to anyone" way, not the biological definition.)
*this assumes a human-like gestation cycle
EDIT: There, Dark Master and Seth, it would appear that i inadvertently addressed your concern. Clearly, my above theoretical assertion is based on a displayed pattern of behavior and not through stylistic choice or stereotypical assumptions.