After watching the Brook fight, Did Canelo say to himself, "It's time"? Did he decide, "That's it. I'm now a middleweight"? Will Canelo fight?
Canelo isn't as skilled as Brook, isn't as fast as Brook and isn't as brave as Brook, he bravery proven by his refusal to fight Golovkin. Canelo won't fight Golovkin, he has made that clear.
If GGG didn't break Kell's eye socket, he might have thought about it for a few more seconds at least before continuing his avoidance.