He could have still been a Crusader, but at Sudeten, he was part of Phelan's force. It says that the wounded from Natasha and Ulric's battle groups were sent with Phelan, but nothing about troops going back to be with the main show. Sumner Johns and Trinary Echo disappear from the rosters after that, for all the scenarios, and are not there at the final rosters in the back of either Wolf franchise.
But that does not mean it had to have happened as cut and dry as that. Agreed. Possibility is good, it's the true comfort food of the imagination.