I don't know that this was necessarily a deliberate choice, but I think Homestuck's disinterest with the culture of labels many of its readers exist within really works in its favour when it compels the reader to seriously consider those things that go unsaid. Like, even when we're told that trolls are technically bisexual, or that gender works different for them, there's a lot more value to be extracted from the text when we're trained to identify the ways in which some trolls are actually gay, or straight, or have very human relationships to gender identity.

Actually now that I think of it, maybe some little part of that WAS intentional, given that all our understanding of trolls as "bisexual" comes from Aranea, whose fixation on labels so often seems to get in the way of what she's actually talking about...