Alert all airlines to the names and photos of all those "terrorists" who want to return.
The airlines CAN refuse to carry people. I am sure they would not want them on their planes!!
Contract of carriage pretty much gives carte blanche to the airlines to do as they wish but why are you so sure airlines would not fly returning jihadis home? Afterall, they did not have a problem taking them away in the first place.
.....because they probably did not know who they were on the way out!