You're misinterpreting what that means.
As far as Ono and the Street Fighter team is concerned, the issue has been addressed. That's how they feel about what is appropriate for their game and their audience.
People may continue to complain, and CAPCOM may react further, but that is yet to be seen. They could change their mind, sure, any time. Until that happens though, this case is still closed as far as Ono cares I'm sure.
As of now, this is the response, and they want to get back to worrying about other things like optimizing their game and developing content for their game, which in the end is far more important than these few frames of whatever.
It's their game and their line. But to them it's about moving on to other things and at the end of the day it's one decision out of thousands to be made on the game.
You may find it arbitrary. To CAPCOM it's where they find what is appropriate for their game and their audience, which means it's their definition. What is defined as arbitrary to you really doesn't matter.
They actually have to make decisions about what goes into their game, not like us. Everything they do is effectively arbitrary. Why is X animation 10 frames instead of 11? Why does this dude have 1 invincibility frame, and another has more? Arbitrary to us, except in completely in context for the developers who are actually making the game.
To CAPCOM someone has to make the decision, if they are OK with it, or if they are not. They made a choice, they can move on to doing other things. That's how work gets done. Doesn't mean it's the right or perfect choice, but it doesn't have to be. I'm sure they are more worried about making a great game than just one character animation.