I personally think that it’s a fundamentally positive thing for people to be able to find ways to see themselves in fiction, and seeing as thematically speaking Bionicle can be argued to reflect trans issues, there are some valid arguments to be had for interpretations of trans characters. Yes, Matoran are innately asexual beings designed to not have any gender dysphoria or the like. But one of the driving points of later Bionicle, and one of the most interesting ideas it had to offer, was that the Great Beings got it wrong (apparently we can blame Velika for that, I guess Velika is Bionicle’s Prometheus). The Matoran, Makuta, Karzahni, and all the rest were created to just be soulless cyborgs fulfilling a purpose, but they developed identities of their own, often contradictory to their arbitrarily assigned roles. And though sex in the Matoran universe does not exist as such, gender roles clearly do, assigned by element. In that way, I can easily see how characters like Midak or Tamaru, who deviate from the assigned characteristics for their element, can be argued to be trans or to represent trans issues.
As for the points about demanding female characters while doing nothing to contact Lego and improve things, yeah, fair enough, you’ve got most of us pegged there. Sad but true, it’s easier to speak than to take action, and I know I personally have certainly been lacking on the action front.