Earlier quoted context omitted.
There's a difference between keeping a secret, and avoiding legal trouble by not specifically naming an employer.
Is Valve really going to file a lawsuit against him and argue in court whether this actually happened or not? They're not. Do they even have grounds to file a lawsuit? Likely not, American courts aren't that sympathetic to libel claims. But let's assume for a minute that what you're saying has some merit. Maybe Valve does have grounds to sue. And maybe they're interested in suing. In that case, is this lousy attempt…
It isn't fair, but that's how it is. Don't poke the bear anymore than you have to. All you have to do is personally anger one executive and they can go after you.