Cyttorak denying Cain power.
Cyttorak found Cain's reason for fighting to be weak, so he doesn't allow him more power. This demonstrates that Cyttorak has certain standards of behavior for his avatars and if he finds them wanting, he'll rescind the power. He doesn't restore Cain's power until Cain embraces his evil ways again, hence, Cyttorak all but dangling the power in front of his face with the prompting about the reason for him to fight Hulk.
Cyttorak commenting of Cain's behavior during Fear Itself.
This reinforces that Cyttorak wants his avatars to behave in certain ways. The only reason he ends up disapproving is due to the fact that Cain is also serving the Serpent due to his possession by Kuurth, as pointed out by Magick. This is why he ends of taking away Cain's powers and giving them to Colossus.
Colossus's normal Juggernaut form &
Enhanced form
These are important because it shows us that Cyttorak can give more power and in a variety of ways. Another scan will reinforce this even more down the road but I just wanted a little more evidence about the fact that Cyttorak doesn't always hand out the same level of power all the time.
Cain being given even more power at one point.
Here, Cain was given even more power after a deal with Colossus and Cyttorak. Again, we see that Cyttorak can hand out power as he pleases.
Heck, Cyttorak even took away Juggernaut's weakness to psionics in this form.
Cyttorak explains why he likes Colossus so much and compares him to Cain.
Finally, we get it straight from Cyttorak. He straight up admits he gives more to Colossus due to Colossus partaking in way more destructive fights than Cain, way more often. Heck, this came about because Colossus tried to get Cyttorak to take back the powers, because he had the Phoenix Force and was technically serving another master, like what happened with Cain in Fear Itself. This was Cyttorak's response and reasoning for refusal.
So, in conclusion, we can clearly see that Cyttorak is where the buck stops. It's up do him to deem if his avatar, the Juggernaut, is acting in accordance with what he wants and gives or takes power based on that.
Note: I'll be heading off to work soon. So any responses or disagreements or questions, I won't be able to answer until way later tonight.