In the regular season Thybulle could have value. But one way players are totally exposed in the playoffs as they can be schemed by a prepared opponent to have a much more negative value. Thybulle is basically the opposite of Kanter and Melo. Makes sense the 6ers have just decided to move on from Thybulle as they are playing to prepare for the playoffs more than squeak out a few regular season wins. The Blazers might not have any playoff aspirations.
Beyond that; defensive specialists are generally much less valuable than offensive specialists. The offense can control how involved those offensive specialists are with the ball so the team can maximize their utilization. However on defense; the defenders team doesn't control who is defending the ball, the opponent can just give the ball to a secondary creator and take the defensive specialist completely out of the play.
Additionally; teams can help cover a defensive players shortcoming with rotations, in a way that teammates can't help each other with a jump shot or scoring opportunity. Coaches can develop defensive schemes.
Thats why you see offensive specialists all over starting lineups in this league, often even on All-NBA teams. But defensive specialists with major holes on offense often get relegated to 3rd string if not just dropped out of the league.