They missed a great opportunity to turn the whole backstory on its head and reveal at the end that the angry, bitter twin was the survivor and that would have better aligned with his starting personality of 'don't bother to help others'.

As it was, I'm starting to lean toward all of the breathings getting similar as they are mastered, or approach the first or perhaps one true sun breathing?

In hindsight, it is at least a little interesting that this Hashira is so green. He obviously hasn't been in a prominent position or life and death battles for long as evidenced by how easy he loses his cool from a little poison and trash mobs. Due to that, I'm willing to assume he's the weakest Hashira currently and that makes this clown battle a little more tense against the number 5 demon with his own brand of autism.