Because it it was a simplistic generalisation that all Muslims travelling to ISIS controlled areas become a threat - yes, they are. They subscribe to a violent interpretation of Islamic scripture. They willing go there, knowing all about the beheading of Alan Henning and the burning alive of Muath al-Kasabeh. I'd say it's reasonable to regard all who go to ISIS territory as a threat.
I'll ask again: even Muslim journalists? (You're previous reply was strangely limited to British Muslim journalists). As a child I also subscribed to the killing of billions, I don't now. By banishing children who enter ISIS territory you are heaping the sins of parents upon children which is... archaic.
instead of merely criticizing the responses on this forum, perhaps you'd like to offer your own solutions. Just a thought.
Is that a forum rule? I don't believe there is a nice neat solution (short of the paradise earth) but I do think your suggestions would exacerbate rather than eliminate the problems. Just a thought.