Even if this was a real terrorist, this is the worst move security services could’ve done.
They could bar a suspected terrorist from entering the plane via a temporary arrest. If they’re wrong, just reimburse the travel costs. If correct, you didn’t let a terrorist possibly hijack a plane.
They could use the “randomly selected for a search” card as an excuse for detailed screening. A terrorist can’t blow up a plane without some sort of smuggled troublesome equipment anyway. If they’re wrong, you spent like 10 minutes searching a random dude. At least you didn’t gave a terrorist chance to hijack a plane.
They instead let a suspected terrorist enter the plane as usual; then tailed him with fighter jets. What the actual fuck was the plan if the suspected person was a terrorist? Blow up the fucking plane so all the civilians inside die?
Imagine the call done to the authorities
“This is airport, we’ve detected a suspicious individual that could be affiliated with a terrorist organization”
“Since you detected him, I assume you’ve detained him? We’ll be sending units”