It is possible that the Jazz really like most of those players(Cooley and Motum) and they decided that they can call Cooley in any time they want from the Stampede, while Motum not having a guaranteed contract, pretty much guarantees that he'll be gone to an European team, where he'd be making better money(he played in Bologna last season). So the only way to keep him as a backup is to give him a contract and include him in the team. That still doesn't mean he'd be getting tons of playing time.
edit: I just checked, it seems that Cooley was in a similar position last year, so I you might disregard what I wrote above...