Curate, connect, and discover
I read a post about Alex a few months ago that basically said Riordan's portrayal of genderfluid people was problematic because of the way Alex explained being genderfluid to Magnus. I beleive they said it was unnatural and that no one would explain it that way.
I think they may be forgetting that Magnus Chase is for young kids who probably have never heard of the term before. Alex explains genderfluidity in a similar way other characters explain mythology. The characters aren't just explaining the subjects to each other, but also the audience. Who are meant to be children.
Of course you may think that its a rather patronizing way of explaining it to kids, which is fair.
That being said, Riordan definitely made many mistakes in portraying his minority characters accurately/respectfully, and he didn't respond to criticism well, but I don't think this particular criticism is fair. If anything it should be a criticism of his writing style.
Of course this is just my opinion, and I couldn't find the original post so I may have misinterpreted it (apologies if I did, feel free to set me straightđź’™)