Well yes, Colossus did only just get the gem. It was a modified version of the canon events of Fear Itself where Colossus became Juggernaut. And during those events, it was shown that Cyttorak is able to fully empower multiple people to be Juggernaut. As Colossus became Juggernaut, and was fighting Juggernaut(Cain Marko), who at that point had become Kuurth, Breaker of Stone. And he had an Asgardian spirit empowering/possessing him on top of his normal powers. And Cyttorak didn't take his powers from Cain until Magik got in his face about it. So I figured with no one jabbering at him, he just wouldn't care enough to take Cain's power.<br/><br/>Also, as in canon, Colossus is very wary of the powers. They're useful, but he's afraid of the price they come at, so he uses them warily and with extreme caution. There are even security measures and failsafes set in place on the chance he has to use his powers and he loses control, since Cyttorak effects him differently than Cain. And he is not so much in control of his powers as he can do the basics because they're pretty straight forward. Run fast in a line, be strong, be tough, etc...<br/><br/>So it's not just something he whips out on a normal basis like his regular powers or everyone elses.  It'd be specifically for really bad situations where it's absolutely necessary he transforms.