Asexual genderfluid haruhi? More like canon
More like headcanon.
Chapter 83 and the Spain bonus chapter of the manga is proof that Haruhi is not asexual.
As for Haruhi being genderfluid, evidence in the first chapter points that she is a person who doesn’t understand the difference between different genders.
More like there isn’t enough asexual and genderqueer representation so just don’t try to invalidate people inserting their own representation where they see that it fits.
What you describe is a headcanon because it pertains to something that is not mentioned in the canon.
If it is NOT mentioned in the anime or the manga, it is not canon, but you can have it as your headcanon.