And while I personally found Gawker trashy and not worth a lot of respect, Thiel had profile pictures on open social media accounts of him shirtless on gay cruises. Short of a formal press release saying "I am gay", this wasn't any particular revelation.
(As to the "well, it's still noone's business" - while I agree, the courts have repeatedly held that billionaires are considered "public figures" "by virtue of the undue or oversized influence they wield or are capable of wielding" - so Thiel had little legal claim to his own situation, so used someone else as a proxy for his own grievances).