Asymmetric career risk happens when you know that the downsides of doing the ’safe’ thing are capped while the downsides of doing the ‘risky’ things are uncapped. Therefore it makes sense that you would be more willing to make risky moves in an institutional context if you know you aren’t going to be judged on your actions either way after you leave (The transient nature of most people at DARPA enables ideas to be revisited.)
People with a web presence tend to be focused on playing status games (People create proxy games for long term or hard-to-measure games) or at least are in a world where they realize that their career depends on their output. Internet people are playing a game to maximize engagement. So being an internet person could be taken as being a signal that a potential PM would have in the back of their mind “what will other people think about this?”
People are more likely to judge a crazy act positively if they know the reasons why it happened. So if the people you care about are a small group of peers (DARPA is relatively tiny and flat) rather than the whole internet it increases incentives to just go for it.
Low web presence also tends to be correlated with a high ratio of doing to talking. DARPA PMs need to think for themselves, be curious, and have low ego
Additionally, less internet presence means less grand announcements and fewer expectations. If you know it’s easy to shut something down it’s easier to start. Contrast this to something like Peter Diamandis and the X-Prize.
Of course, it could be more simple and DARPA just doesn’t like people who are too loud because they like to keep things hush hush. Opacity is important to DARPA’s outlier success. But then maybe there is something to keeping things hush hush. If you keep things hush hush, you don’t have to deal with lock-in from publicly announcing you’re going to do something.