"What legitimate reasons are you applying to justify treatment of any or every person on the planet as potential threat"
Because they are? Approximately zero risk, true, but slightly over zero. Its a pretty simple straightforward game theory problem. Whats the total aggregate sum of the trouble you'll get into by letting 1 out of 100 million terrorist thru, vs simply stamping "denied national security" on any random visa and stonewalling? In fact the guy who dared complain about it is probably now on some secret NSA list, and perhaps also now on the no-fly list. That'll show people what happens to complainers, hopefully that prof never has to fly anywhere again for the rest of his life... and probably his families lives, too.
Note, I'm not supporting an unjust system, just explaining how it works from a game theory perspective. I don't see why any individual inspector would ever permit a visa unless there's some kind of piecework payment system or a really good non-retribution system (anonymity?). If a terrorist ever got past them, there would be demands for punishment. Therefore "the system" is going to select for inspectors who are either reckless, careless, actively working against the interests of the USA... None of which will probably have ideal outcomes.
You are completely ignoring the negative effects of these decisions to exclude. Those decisions do not happen in a vacuum. Every one of them has an associated "negative" effect that also accumulates.
OK, then explain the Tsarnajevs (the Boston bombers) getting past even with multiple terrorist flags? If the system is stonewalling and so tight, then why were they successful in going to terrorist camps and then coming back?
The current process acknowledges the fact that there will be a number of false positives, probably an order of magnitude higher than true positives - a class of people which the system aims to filter impeccably.
However, we should not forget about the sentiment this process brings about. It leaves a very poor taste and even hurts and insults a lot of people and the cost of losing those talent and taxes thereof could be manifold.
Because they are? Approximately zero risk, true, but slightly over zero. Its a pretty simple straightforward game theory problem. Whats the total aggregate sum of the trouble you'll get into by letting 1 out of 100 million terrorist thru, vs simply stamping "denied national security" on any random visa and stonewalling? In fact the guy who dared complain about it is probably now on some secret NSA list, and perhaps also now on the no-fly list. That'll show people what happens to complainers, hopefully that prof never has to fly anywhere again for the rest of his life... and probably his families lives, too.
Note, I'm not supporting an unjust system, just explaining how it works from a game theory perspective. I don't see why any individual inspector would ever permit a visa unless there's some kind of piecework payment system or a really good non-retribution system (anonymity?). If a terrorist ever got past them, there would be demands for punishment. Therefore "the system" is going to select for inspectors who are either reckless, careless, actively working against the interests of the USA... None of which will probably have ideal outcomes.