Well, he didn't get it from snorting coke... and rich people don't usually go around sharing needles, but maybe... Perhaps he needed a blood transfusion and was one of the unlucky few... Or maybe some lunatic with a hypo full of aids blood broke into his house and injected him in his sleep...
He may have contracted it from hetero sex in which case males are more likely to give it to females due to biology... or he could have been playing catcher, which comes with a 20x greater risk of infection from an infected partner. I guess it's just a numbers game. I mean, they don't market Truvada to gay men for no reason, do they?
So no, I don't think gay sex is the only way to get HIV... but it seems to be the preferred method.