You use the old "lack of evidence isn't evidence of lack" argument. While true, insofar as that goes, it does not prove the positive assertion that he ever participated in homosexual activity.
For example, I could claim that Alexander was a cannibal. You could counterclaim that he never ate human flesh, but there is no evidence possible to prove this negative, short of a totally trustworthy account of every meal Alexander ever ate: an impossible standard of proof.
But, as I am the one putting it forth, it is not for you to negate my argument, but for me to support it. Likewise, it is up to the pro-homosexual theorists to support their positive assertion, or they remain only speculations, mere fantasies no more valid than one of cannibalism. It is possible, through one point of evidence, to prove a positive; it is impossible to absolutely prove a negative.
To date, neither you nor anyone else has offered a single proof that Alexander was anything but 100% heterosexual. All the available evidence indicates nothing else. Until such a proof is produced, the homosexual theory holds no more credibility than the cannibalism theory.
You use the old "lack of evidence isn't evidence of lack" argument. While true, insofar as that goes, it does not prove the positive assertion that he ever participated in homosexual activity.