The release policy you initially had questions about was focused on releasing applicants from current AFSC and not from Oversea and AAC 50 tours (assignments). This is understood from the statement "The Air Force does not anticipate significant impacts to any one career field, as the number of Airmen selected for Special Tactics are minimal" in the press release pertinent to the Apr 2015 policy memo. For a small unit having AAC 50 assignment needs the retrain approval loss can be cause of significant impairment to the unit fulfilling its Designed Operational Capability and obligation to be operationally ready to deploy/employ for any or all unit assigned missions within the unit's designated response time.

To get release from an AAC 50 assignment needs an understanding of why it exists and that release from such assignment is not the same as release from current AFSC.