There aren't that many records of the period.
The New Testament has thousands of times more documentary evidence, and it is controversial.
Imagine having a few late-dated manuscripts far removed from the time and making authoritative statements about the era in question, much less about an individual.
One thing that is beyond serious dispute about the era in question is that homosexuality didn't just speak its name, it shouted it from the rooftops. If Alexander wasn't having homosex then he was probably just about the only one..
Moreover, the Romans took a much more ambivalent view on the matter, and since they revered Alexander there is rather little reason I can think of why they would've fabricated such a thing.
God**mn Faggots!!!!!
(Not that there's anything wrong with that)