Regular readers will remember that I recently warned Facebook kiddies to be very afraid because their new boss, ex-Google honcho Sheryl Sandberg, would soon begin thinning the ranks at Facebook: “Slowly, one by one, she will start picking you off. Like a predator in one of those sci-fi movies where people keep going missing.”

Sure enough, now comes word that the company’s CTO, a guy who has been pals with Mark Zuckerberg since high school, is leaving for no apparent reason. Official version is that Adam D’Angelo (photo) wants “to take some time off.” Now listen, friends. Kids in their early twenties do not take time off. Especially when they’re working for the hottest get-rich-quick startup in the Valley. These folks do not leave because they need a break and want some R&R. They leave because someone gave them money to go away so that someone can bring in one of her friends that she trusts more or believes is more capable.

Nevertheless the ever-clueless CNET describes the resignation this way: “It’s kind of like this: an indie rock band gets signed to a major label, and after a taste of the high life, the bassist jumps ship.”

Um, no. It’s like this: A garage band gets signed to a major label, and the label assigns a producer to their album, and the producer says the bass player’s gotta go. I mean, you’ve seen Wayne’s World 2, right? Or, for the older folks, does the name “Pete Best” ring any bells?

Perhaps you were wondering why ZuckerBorg has embarked on a one-month “Vision Quest” to India and other locales for “pleasure and contemplation”? Well now we know. The poor kid can’t bear to be around when his pals start getting SandBorged. What a sweetie.

FWIW, I was talking to the Beastmaster over the weekend and he says he’s heartened by the fact that Mr. Fleece-and-Flip-Flops can’t handle watching the carnage. He and Monkey Boy see this as a sign of weakness. And they’re right. The true killers (and I know because I’m one of them) don’t mind seeing our friends getting tossed under a bus — in fact, we get off on it. Larry, who’s the sickest of us all, actually videotapes his firings and then watches the tapes afterward, while being pleasured by interns.

But not little Zuckerberg. When put to the test, he blinked. Nice work, kid. You let the Valley VCs and private equity sharks into the pool, and now the sharks are eating your friends, and you’re off in India, hiding. What a mensch.

The question arises: Who’s next? Will Zuckerberg’s sister, Randi Jayne, maker of painfully bad songs and videos, gets booted from her sweetheart job in “marketing”? Doubtful. They’ll keep her around just so Mark can feel safe. Worth wondering, though, is what role Zuckerberg will return to when he completes his Vision Quest. Smart money says he gets pushed into some kind of “visionary” role so that the new team of Valley veterans, installed by Facebook’s investors, can finally complete their takeover of the company.