Pederastic relationships in Greece were based on a hierarchy of power. The older man of higher status had a teenager of lower social status "serve him" in exchange for social favour and receiving a higher social position. It was an exploitative rapport written inside a highly heteronormative viewpoint, that of bottom = woman = inferior. Basically an exchange, not equivalent to a male-female relationship. This kind of stuff would be classified as statutory rape today and would be illegal. It had nothing to do with the concept of an equal, loving relationship or liason where both parties were into it, like it is today. The Greeks had no concept of romantic love between men.
Nobody knows if Alexander was actually gay the way we construe it now. He probably wasn't. His supposed "gay companion" was of a profoundly lower social status. If he had sex with him, it would be seen as a symbolic act of dominance and opportunism, not love. As usual TV makers took something complex and tried to turn it into some sort of social commentary victory that isn't accurate.