User blog comment:Merp123/where is thorn?!?!?!/@comment-3168373-20130304021121

This is what happened. Originally, the Youngling arc was to air separately as a special, and the Clovis arc was a three-parter and the Thorn was one episode. The crew then decided to replace those four episodes in total with the youngling arc, replacing them in S6, so some material has to be removed from that season to fit the Clovis and Thorn episode(s).