Hux has always known that when the time was right, he would make a play to assassinate Snoke and take his place as Emperor. It's just a matter of time. Killing Kylo is, regrettably, a part of that plan. Ren is too dangerous, too fanatically loyal to Snoke, and frankly too much of a loose canon to ever have a place in Hux's Empire. When the time comes, putting a blaster shot between Kylo's eyes will be the first step in Hux's plan.

Snoke knows that Hux is young, ambitious, the public face of the First Order, and commands the personal loyalty of a large number of their Stormtroopers. For the moment he's useful exactly where he is, but Snoke has always planned to have Hux killed eventually. That's why he placed Kylo so close to him. Really, the Master of the Knights of Ren wasting his time chasing ghosts and slaughtering peasant villages? Kylo's real mission is and always has been to take Hux out when the time is right.

None of this stops them from banging.