Leave that for the courts to decide because we citizens of whatever country are the first line of defense, if a person is suspected of any affiliation to a terrorist group they should be black flagged until PROVEN otherwise. Try waking up to watch thousands of your brothers and sisters die and you may have a different perspective.
But you aren't leaving it to the courts to decide if you want to black flag people who you have
no evidence against. Anyway, all the increased security at airports is meant to stop bombs from getting through (probably not 100% foolproof, but that's not the point here).
By that reasoning, I wouldn't have gotten into the US when I visited NYC earlier this year. Why? Because I've been to Dubai and the customs guy didn't like the Arabic stamp from Dubai on my passport. On questioning me, he discovered I'd actually been to NY last year too, after I'd been to Dubai (which was quite a few years ago) and because I'd been let in before, he relented and waved me through.
What you are suggesting is akin to the Chinese history where the Red Guards eventually attempted to destroy anything associated with traditional or foreign cultures and was a horrendous example of completely extreme, and in many cases unjustifed, persecution. Thousands of Chinese died around the time of the Cultural Revolution thanks to this extreme persecution so don't give me BS about seeing my 'brothers and sisters' die because trust me, my family's seen *plenty* of it. My mother to this day refuses to visit China because she is absolutely terrified that she will be thrown in jail or killed even though she has done nothing wrong.
Bear in mind that many of the names that ended up on the Chinese blacklists were as a result of hearsay and little or no evidence. Friends turned on each other to ensure they didn't end up on the blacklists themselves. Pointing the finger at someone else, no matter whether guilty or innocent, meant they had less chance of ending up on the blacklist themselves.
So I make no apologies for being 100% against stopping people from getting on planes even if they are on a blacklist. If there's
evidence that they are potential terrorists, fine, stop them getting on a plane. If all you have is a "susipicion", absolutely no way.