Your lack of awareness of the world around you doesn't make you an expert in what is or is not correct: that has been delegated to the group being represented, by consensus (not by individual).
As for the current thread, let me try a third time: it doesn't matter a whit what these people said. They could have been talking about how nice a day it was to be going home. They could have said that they hoped everything went well. It doesn't matter. (Some have claimed an inability to grasp this; that's unfortunate, but that's not anyone's problem but their own.)
What matters is that a third party overheard something which they regarded with suspicion, reported it, and correctly triggered additional screening. This family was (apparently correctly) cleared during that additional screening.
The airline would likely have held the flight pending the outcome of that additional screening, in case further actions were required on their part to remove additional passengers or luggage. But whether the airline then permitted this family to reboard this flight, or declined them travel that day (based on the costs the airline incurred in delaying the flight) is up to the airline. Apparently the airline chose to refund the fares paid, and sent the family to another airline (inviting them back in the future, according to reports).
Was the comment suspicious? We really don't know. We have the family's report (are they really going to say now that they said something suspicious?), but beyond that all we have is that it was suspicious enough to someone that it was reported. And being reported, it appears to have been correctly acted upon.
Note that none of the above had anything to do with the family's religion. Only after the fact are people asking if this family was singled out for their religion and making religion an issue. Was the person who reported the suspicious remark affected by the family's religion? There is nothing in the story to substantiate that claim - just the apparent xenophobic reaction trying to create a bigger problem than previously existed by claiming that they were singled out because they were Muslim.