It's pretty simple.
In Kevin Owens onscreen character you have a fat unkempt neckbeard who is largely self-centered (except for this wife & children) who will stab friends in the back to get what he wants. It's no wonder he's the IWC pin-up of the moment, as a large amount of them look and act exactly like Kevin Owens albeit in virgin form, making them think that if he can make it, so can they - if they could actually walk 50 metres without being out of breath. Also another difference is that since he is married with children, I doubt Kevin keeps moaning about being friendzoned and joining MRAs in response.
John Cena on the other hand, is the consummate pro-wrestling professional. He doesn't take offence at being asked to work on a mid-card title to help bring through up-and-coming talent. Fellow wrestlers and others who have worked with him have very little bad to say about him and note his work ethic. He is arguably one of the most selfless people in an industry full of egos, a great example being the work involved with the Make-A-Wish foundation in seeing what must be close to 500 children through the charity at this stage. That is a huge emotional burden he carries and one I certainly couldn't do at even 1/100th of that amount. The child he brought attention to on Raw is because he knows he means a lot to such children and wishes to keep them happy to either help their spirits in their battle, or in many cases in their final days. Last Monday night was nothing out of the ordinary for him when it comes to interacting with sick children. If you feel that child was exploited, why not ask that child and his parents if they felt he was exploited? I think it would be safe to know what their answer would be.
It isn't John Cena being selfish here, nor is it Kevin Owens. It is a large contingent of IWC neckbeards who haven't had a shower or bath in a week who try to deflect their own selfish desires by attacking those who work hard to better themselves beyond being a basement dweller, attacking those like to give something back rather than just take, take & take. Those of us fathers, that is right, fathers, who have respect for Cena as a character on TV and as a man recognise how hard he has worked his ass off to get where he is today and also worked to give some back. Many don't. Is he the most naturally gifted pro-wrestler on TV? No. Is he the most technical pro-wrestler around? No. Is he the most hard hitting shoot-fighter in wrestling? No. Is he the most entertaining? The answer is a clear yes, and he has be very consistent in delivering quality matches on PPVs over a number of years. It is only natural that children will look for role models beyond their fathers and mothers or anyone that is a father or mother figure to them, but that's not because they fail at being a parent or guardian, but because children will be influenced by many adults as they grow up. For my son, he could do a lot worse than Cena when it comes to role models. I won't be wearing a John Cena t-shirt, but if my children want one and I have the money to spend, they can gladly get one.
Not much more of a point to be made. I've said it before and I'll say it again. John Cena is the man that the neckbeards can only dream of being.