I saw this on Twitter last night and one comment gave a perfect response to this. There are two ways you can believe the claims of Elagabalus being "trans".
1) The claims are false and overexaggerated by his political enemies to make him look insane.
2) If they're true, why would you want to be proud to claim him as one of your own considering the dude was straight up insane?
Here's a few things he supposedly did.
1) He was also a sexual debauchery and complete weirdo who would serve fake food at parties and filling pools with wine.
2) During a party, he allegedly ordered a deluge of rose petals to fall from a ceiling mechanism, burying guests to the point of suffocation.
3) Dangerous Pranks: He released tame lions and leopards into his palace to terrify guests.
4) Public Baths: He opened the imperial baths to the public to watch people bathe naked.
By all accounts, the dude would not be someone I'd want to claim as trans if I was one