Someone is really salty over people trying to be reasonable and speak facts over the truth of Lily...
No, it's that posting spoilers in comments without the spoilers tag surrounding it is a bannable offense if done often enough. And that policy tends to be "tag what you see" and that gets difficult sometimes.
I know the 'tag what you see' rule isn't absolute, but breaking it to spoil something probably isn't the way to go. At the very least, though, use spoiler tags in the comments... yes, the meta stuff about otoko_no_ko tags is also a spoiler.
If it's "tag what you see," you can argue that all the otoko_no_ko tags should be tagged as girls. So what would be the line at that point?
Default to official information. Lily is listed as a girl on the official website and the show itself treats her as a girl.
We don't tag chevalier_d'eon_(fate/grand_order) as a boy or a girl until we see what they are packing down below, because the source material explicitly says that it depends on what they need to function for the moment.
Also, we go by artist intent (whenever interpretable) for tagging genders. I.E. gendswapped characters are tagged as the characters are depicted (like all those "Shimakaze-kun" images, or Astolfo in a bikini with breasts but no groin lump) rather than their canon sex. Artists up to this point were drawing girls, so there's no reason to retroactively change the gender of the tags. It's especially absurd to tag "boy" when Lily's been portrayed naked with a visible vagina, after all. The ones that should be tagged as 1boy now are the ones that actually have some hint, like a "#spoilers" or a groin lump or something in the tags, comments, or image itself that implicates the artist intends this Lily to be seen as male.
That's mean you will damn tag Astolfo as gilr just because they drawn him as such? Soft belly, cute figure, feminine ass, not bulge. Of course not, step up dudes.
Astolfo is presented as a cross dressing dude from the moment he's introduced and was advertised as such and I'm not sure how you can call a flat belly, slender but broad torso and a rectangular figure a girl's body.