This is best route for it to go.
The best explanation is for Jimmy to say that he's always been his brother's keeper, and has always tried to protect him. This sometimes results in him doing shyt that would piss off his brother but no matter what, Jimmy had Jey's best interest in mind. He saved him from Roman twice, but this time, he was saving Jey from becoming what Roman had become.
Jimmy watched Roman abuse Jey and eventually it got to the point where Jimmy fired the first shot to protect Jey because Jey hadn't built up the courage to do it himself. He showed him the way as an older brother should. And then when Jey pulled that trigger, Jimmy was right there to help Jey get his revenge at MITB, when Jey pinned Roman. In Jimmy's mind, that should have been the end of it, and they could go back to doing what he's always wanted them to do, which was be the best team in the world. Keep in mind, right before Jey said he wasn't with Roman no more, Roman and Paul said Jimmy never wanted Jey to be the Right Hand Man or be by Roman's side, and Jimmy confirmed that was the case. They never elaborated on why.
Then Jimmy got put on the shelf by Solo and Roman, and instead of being by his brother's side, in Jimmy's mind, Jey "exploited" Jimmy's sacrifice into a match for the title as well as the role of Tribal Chief in the family. So sadly Roman was right even though Jey initially asked for a fight with Roman to avenge his brother and show Roman what it was like to have your own family take everything from you.
Meanwhile Jimmy is like ...
"I thought we both had an understanding that neither of us wanted to be the Tribal Chief..."
"I get my ass whooped because I helped YOU get your lick back on Big Uce, and you use that to go for it all?"
"Why the fukk do you want to be Tribal Chief when you see how that shyt has poisoned Roman and how it makes him treat his own blood?"
"I've felt first hand what that damn lei does to people's mindset... I know you, Jey... I cannot let you become Tribal Chief. This is for your own good, and I'll be damned if you use my trauma for your personal gain... even if you were finally ready to be Main Event Jey Uso."
There has to be actual depth to it, regardless of how it goes. It can't just be "Big brother is mad/jealous that little brother stepped outside of the shadow."
as fukk when Orton won the title at Summerslam 2004.
more reason to pull the trigger can you imagine the reaction 
