The link in that tweet isn't working for me, but it's not hard to see that of course there are problems with how KH handles girls.

• There are six. Six named female characters (not included here: Kairi's grandmother, two of the Foretellers look like they're probably female but they have no personalities or dialogue or anything yet so I'm not counting them at all, Sora's mom). I can't remember the exact number of male characters, and it kind of varies depending on how strict you get about "their own person," but there's well over twenty.
• it's been nine years since KH2 and Kairi has gotten maybe seven minutes of screentime since then, almost entirely in BBS plus her cameo in 3D, and I am weeping bitterly
• KH manages to barely squeeze by in the Bechdel test, because there are a lot of worlds where there's one or no girls (KH1 has three worlds where there's at least one girl in the source movie but none in game) - and when there are two or more in the same space, they rarely even talk to each other (Alice & the Queen of Hearts and Ursula & Ariel are the only real exceptions in KH1 - Yuffie and Aerith don't talk to each other, which I never noticed. KH2, again, is a little better, but still pretty sad. BBS does better by making a girl playable, so there's always at least two girls in a world). I'm not even touching the "about anything but a boy" part here

However: when they do get screentime, they're handled pretty well. It's easy to get a clear view of Kairi's personality and likely character arc, despite how few scenes with her there are, for instance. I have plenty of beef with KH over this stuff, but it's mostly about screentime (and maybe stuff like everyone uncomfortably hitting on Aqua in Olympus Coliseum, but). I wouldn't call it overly sexualized.

That said, Nomura seems to have a tendency to just... leave girls out. Look at FFXV; every party member confirmed so far is male. The only female characters we've even seen are an unnamed girl from the character lineup, 'Luna,' 'Stella' (who may or may not still exist), and apparently there was a fourth shown in a magazine preview recently?

This is especially weird to me given that every FF since VII onwards has had a more or less balanced party in terms of gender, which was a big draw for me in the first place.