It appears that he was incensed about Gawker outing him almost 9 years ago in what was actually a rather adulatory article. He had been out in all but press release at the time.
It turns out that this incensed him because he literally made his fortune off of gay bashing when at Stanford University:
………So his declaration of outrage is fueled by rank hypocrisy.
On the Gawker site, the most popular—I don’t say best--defense appears to be that “outing” Thiel was beyond the pale—so the suit accomplishes belated justice (that’s dubious in itself). Setting aside whether an outing actually happened or what prevailing ethical/journalistic standards are, I think Thiel’s time at Stanford (overlapping mine) bears renewed scrutiny.
Keeping it brief: Thiel essentially got his public start by founding the Stanford Review. That publication quickly, if not at its inception, was devoted mainly to “anti-PC” arguments, defending in particular fellow reviewer Keith Rabois, another future PayPal zillionare who, as a Stanford Law student was involved in "screaming 'Faggot! Hope you die of AIDS!' and 'Can't wait until you die, faggot,' in the direction of the resident fellow cottage of lecturer Dennis Matthies.”
According to a Stanford news release at the time: "first-year law student Keith Rabois ... sent a letter to the Stanford Daily confirming the allegations."
"Admittedly, the comments made were not very articulate, not very intellectual nor profound," Rabois wrote, according to the news release. "The intention was for the speech to be outrageous enough to provoke a thought of 'Wow, if he can say that, I guess I can say a little more than I thought.' "
Both Thiel and Rabois were/are gay.
This wasn’t just a youthful indiscretion. ... Thiel rode the incident to a book deal and publication in the Wall Street Journal. I assume his conservative bona fides, rooted here, played a serious role in his public profile and early business network? They also weren’t straightforwardly voicing some political/religious position: they were rather rancidly scapegoating other gay men as part of some closeted psychodynamic.
Will Bunch has the most succinct description of what is going on here, "Thiel's Gawker gambit lifts the veil on how the American kleptocracy hopes to control the American media in the 21st Century -- by buying and controlling some key news sites...and using their endlessly deep pockets to destroy journalists who are non-compliant."
I would also direct you to essays from Feliz Salmon and Bob Lefsetz.
I would also note that Theil is a reactionary nut-job, (scroll down toward the bottom) who opposes women's suffrage, supports the establishment of floating cities exempt from law, and funded James O'Keefe's successful jihad against ACORN.
There is nothing inherently wrong with being a rich nut-job. Our history is filled with this.
But when that rich nut-job begins to think of themselves as a God, whether the Randian Übermensch in the case of Thiel or the brothers Koch, or an actual denizen of Olympus in the case Gaius Julius Caesar Augustus Germanicus (Caligula), it's the rest of us who bear the cost of their delusional excess.