I don't remember how many times I said this, but I tell it for you.
1 frame CPU behavior is programmed by Brawl developers, not by KingClubber.
Play with CPU in Brawl, and you'll notice the same thing.
"Fixing" the behavior is necessary as many of users claim though.
By the way there is also a wide-spread misunderstanding that CPUs read your inputs.
This is wrong since even if they do it, they cannot predict what will occur next frame.
To know it, they need to run PSA scripts to calculate hitbox size, hurtbox size.
Also they have to take into account stage data, bone position after certain frames, etc.
It's unlikely that CPUs do such a too complicated things, considering how lazy the Brawl AI programmers were(too fast reaction, too many hardcodes are the examples).