Technically, conditional loan can be given to any players, but only last max 14 consecutive days. Also, the League has to approve and they can decide the team is just trying to go around waiving the player and refuse it, so you want to be sure Struble haven't played for like a full month before requesting one.
But management failed him. They should have sent Struble down once Xhejak took over the 3rd par LD spot back in November before he played enough game to lose his waiver exemption (if I remember right he had 21 games he could play this year before it did).