My spells on what I presume to be the Expanded Selectee List for domestic travel have followed one way non-revenue tickets in and out of Istanbul. Never been SSSS'ed or intercepted by the Immigration Advisory Program on a simple RT. We don't have enough data points to say definitively what is going on and the risk of being flagged surely varies across demographic groups, among other factors - but it does seem like one way flights out of at least that part of the world may still be of concern.