There's been multiple recent manga published in mainstream sources like Ayakashi Triangle and Zenbu Kimi no Sei that deliberately subverted their cishet potential to be brazenly queer instead. All the details align with Hodaka being genderqueer, they've even told Chihaya "I get to be a girl and I get to be with you, two birds with one stone!" to reassure her they're fine with the curse. As far as I'm concerned we should already be avoiding he/him pronouns based on the text in front of us without even reading into meta things like the aquarium date, and it would be very foolish to assume "oh he'll just end up a guy in the end".
ps: if you haven't read it, Zenbu Kimi no Sei is complete on Mangadex and is very similar to this except they're BOTH constantly switching and it's more comedic focused. If you like this manga you'll probably like that one :)
I doubt he'll end up as "just a guy" in the end, but I still think it's pre-emptive to avoid using he/him when the text has also made it obvious he's still uncomfortable with being transformed into a woman and that there's more to work on there in how he views it. And I definitely read the reassurance there as him jumping to trying to make her feel better despite how he feels uncomfortable.
Like, even if he ends up being 100% a trans woman, this is still something thrust upon him that he's trying to figure out, and we don't know how the cards will fall, especially because I'm almost certain the source of the curse will be addressed. I feel like he might end up bigender in the end, feeling both equally a man and a woman.
Also, as someone who is a nonbinary butch, I'm kinda annoyed at a common presumption that entering an enby space always means detachment from your AGAB. I still identify as a woman and use she/her even tho I'm absolutely also nb. Hodaka's gender identity being more complex than "just a guy" doesn't mean being a guy won't be an important component of the end result.