Don't be. TSA is stupid theater, they suck, but probability of anything happening to you is very low. Probability of anything beyond mild irritation happening to you - unless you one of high profile people that Powers That Be have a beef with - is vanishingly low.
Yes, it still happens - millions pass through TSA every day, and you'd have a number of cases where usual silliness rises to the level of dangerous idiocy, and these cases would be widely publicized and criticized, as they should be. But pure numbers game suggests your chances of becoming one of those is very small. If you take some basic precautions - like not standing out too much, being polite and not arguing with them, however stupid the proceedings look, etc. - even smaller.
In fact, on my latest travels, I personally have had much more irritating experience with London security that with TSA. On top of everything TSA does (which they did too), London people were severely understaffed for some reason, but if you think that made them move at anything faster than a glacial pace, you'd be so wrong. They were so Zen I'd be envious if I wasn't so concerned about missing my flight because they need to swab my books and slooowly bring it to some mysterious machine and slooowly come back and so on... But still it wasn't much more than mild annoyance summarily.
> But I am scared I'll get into trouble on the border because of my HN and Facebook posts (e.g. against US drone strikes).
Nobody cares. Really. They don't have resources to read every HN thread.
The good thing I'll say is that somewhere around 57 million people visited the US last year. 99.9%+ had no trouble other than long lines and the general frustration that comes with long distance travel. So your fears, while completely understandable, are also very, very unlikely to cause any actual trouble.
Like, at levels only seen in 1 out of every 100,000 visitors, making it quite likely you'll be one of the 0.1-% percent if you hold these extreme viewpoints?
We get it, people who comment on sweet puppy Instagram posts aren't under threat. Sure. But the IT folk, especially people having access to sensitive information or white/black hats can definitely expect a plethora of insolent questions at the airport, asked in small creepy rooms somewhere at the back, from people who refuse to even identify themselves. Is that even legal?
Shall we also mention the looming danger of own laptops being banned on flights? Either use a Chromebook-like device (which, I have no doubt, will steal your private data, why else would they setup such a honeypot anyway) or GTFO, that's USA's policy.
I've made up my mind. I am not going to the USA for now. There's undoubtedly a huge pool of interesting people who can make some of my business dreams come true there but I am not sure being recorded in an unofficial "special target" list for life and having my devices every time I go confiscated is worth it. I'd say no.
(I exaggerate a bit of course, but to the average guy like myself losing even a $250 throwaway device is something that I will feel.)
So he probably was on some kind of a radar. Are you? Then you concern is completely warranted. Are not? Then it's not.
Criticism of TSA are certainly fair, but as someone that flies to the US from Europe monthly, the fears are definitely overblown.
Seriously, don't sweat it. The fears are overblown and not based on any actual data other than anecdotes from highly vocal bloggers/etc.
About 1 million visitors a day enter the US through airports in the US and about 360 are denied entry -- most of those because they had prior visa violations that deemed them inadmissible and others because they didn't have a valid visa. So 0.03% denied entry. In the U.K., that percentage is about 0.02%, just for comparison.
I think you're missing a 'not' in there somewhere. :)