Personally, I don’t think the lack of a term for male giants in the size community has anything to do with gender politics. I think it’s just because ninety-nine percent of the size content that features giant people is focused on female giants. It’s because giantess content is MUCH more popular and visible (and prolific) than giant male content. The GTS people have a louder voice, as a group, so it’s much easier for them to coin terms that suit their needs and to have those terms catch on. The SW people can coin their own terms too, of course, but those are much less likely to catch on and become commonly used, because they don’t get tons of use and aren’t being constantly reinforced, except maybe in very small groups.
Also, people who like giantess content tend to pay very little, if any, attention to other size content that isn’t giantess-related. If they don’t intentionally go looking for it (and why would they?), they’re not likely to see it in the first place. For them, it’s as if the rest of the size community doesn’t exist…they live in a bubble. If something doesn’t exist in their world, they’re probably not going to feel compelled to create special nomenclature for it.
It’s the same reason why normies don’t have a word for male giants: because they spend almost zero time thinking about giant people (of either gender). Why would they need special vocabulary for something that simply isn’t on their radar? Even in fiction, giant people are not common. The lack of vocabulary comes from a general lack of caring.