There's nothing indicating that any of those factors by itself would make you a person of interest.
And I'd guess the FBI would be a really bad service if "uses encryption" or "camping" by itself would be considered as a strong signal. The noise would be too big.
Now talk about someone who has a history of violence, takes long camping trips with a large arsenal, suddenly dropped all non-encrypted means of communication and is obsessed about books on chemical warfare and terrorist attacks. If it were your call, would you dedicate attention to that person?
More importantly, it's probably used to screen out people who don't belong. You can be damn sure anybody who is an actual terrorist uses encryption. Most harmless religious camping enthusiasts do not.
Actually, a surprisingly large amount of terrorists do not use encryption (or at least not on purpose.) For a recent example, after news media widely reported that the Paris attackers used encryption, it turned out that they actually did not [0], and instead simply used common messaging apps. That didn't stop the FBI from using the attacks to denounce encryption, of course.
In reality, using encryption isn't going to help you all that much if a government entity thinks you're suspicious. It may make it marginally harder for them to be suspicious of you, but that's about it. If they want something, and 'encryption' is in the way, 99.9% of the time they have a way around it. A very relevant, and very hilarious article on this: [1]
The penalty for misclassifications is higher for false negatives than false positives. In fact, what happens if the FBI exhausts its budget investigating the positives from this classifier? Do they try to improve the classifier accuracy or do they seek a larger budget along with the prestige of playing a bigger role in the War on Terrorism?
I don't think camping fits. Take out camping and you get a person with a history of violence, a large arsenal, obsessed with terrorist books. Still pretty scary.
Technically speaking I really doubt interest in camping is any higher amongst terrorists than the population.
Has the subject participated in activities that simulate military or operational environments?
So motorhome and marshmallows with your family at Big Bear Happy Camp probably wouldn't count, unless you're planning to kill everyone by making them eat s'mores until their blood sugar spikes.
Perhaps terrorists with camping skills have a higher threat potential? It's not just about P(terrorism | camping) - they also care about the expected value of terrorism plots involving particular suspects.
Like, I'm not even sure that terrorists are more likely to be known to own guns. The EV of terrorist plots involving gun ownership are higher, though, so more investigation ought to go there.
You make a great point about expected value of damage done, rather than focusing on the probability of an attack. But I think an attack with guns has a low upper limit on the number of people you can kill (maybe around 100, plus or minus?) before an armed response is mobilized. Things like nuclear, chemical, biological attacks or bombs bringing down buildings scare me more from a statistical standpoint.
I'm pretty sure that P(bombs|guns) > P(bombs), so my point stands. It's a mix of guns being dangerous, as well as gun possession being evidence of possession of other dangerous things.
How many non-technical people do you know that use encrypted email on their personal email accounts?
There's nothing wrong with using PGP, for example, but if I found out my totally non-technical neighbor was using PGP, I would probably still give them the benefit of the doubt, but I would raise a flag in my mind and watch for other flags.
Actually, I looked at the encryption question specifically. The question is: "Has the subject engaged in or discussed tradecraft to contextually hide their online activity different from previous activity?"
So, if you're always encrypting everything, the answer here is no. Dude always encrypted everything, dude still encrypts everything.
They are flagging if you suddenly start using an encrypted communication service for specific things, as another indicator something's going on. That's fair enough imo.
Also, camping and survivalism? These seem fairly orthogonal as well.