I somewhat disagree (and somewhat agree).
I wouldn’t be surprised if you were inspired to write this guide after fighting me, because right now I am stupidly belligerent with this move. I’ve been testing it online to see how useful it can be and I don’t mind looking stupid while doing so, but I imagine it can be frustrating for other players to watch me keep using that move while they keep punishing it.
For me this is one of the most interesting moves in the game.
The first hit is extremely quick, not easily reacted to (the second hit definitely is easy to react to for invincible moves and even for blocking), and both hits can be used as anti airs.
If the second hit connects then you get to combo into super.
The two hits even combo into themselves from the right distance, and this distance is easily obtained by jumping back from the opponent at point blank range, or the distance between the characters at the start of the match.
The first hit is really difficult to react to and the distance between where the first hit crosses up and where it stays in front is very close range and is hard to judge, so blocking it each time is going to be tricky, and reacting to it (the first hit) with an invincible move is difficult.
When done at point blank range the first hit will cross up. After that the second kick will whiff and I’m yet to find a character that can punish with more than one hit at that distance (edit: Setsuki can). Grave is the only one who can reliably mash his C at all ranges to punishes that second hit when it doesn’t combo, Jaina, Geiger and Rook will whiff their C if they are mashing it when Setsuki uses B at point blank.
Fireballs are easily reacted to: if Jaina or Geiger use B at the start of the match, Setsuki can react with B and it will combo. For some reason this doesn’t work on Grave. If you B without him moving, it will combo, but it seems like the way he leans forward when he uses B makes his hurtbox extend and then the two hits won’t combo, so you need to walk forward a little bit.
Because of the all of the above, this move becomes most interesting when Setsuki gets a life lead. She already has some great mix up potential, but throwing this in there makes that mixup potential even better because its range is so deceptive and done at the right distance she will only be punished for 1 health.
All of this doesn’t mean the move should be used excessively, but I would not say the mixup doesn’t work, you just need to be smart about it and use it amongst all your other pressure tools. Empty jump to point blank B is a nice little thing to throw in, for example.
Grave is probably the one to be the most careful against, his C will never whiff even when you do point blank B with max range whiffed second hit, but this was already a difficult match up for Setsuki.
Out of interest, here are my findings for B when it’s done from distance X and point blank:
Grave: Should always mash C, if the first hit of Setsuki’s B connects C will still win outside of the combo.
Rook: f+A to punish point blank, Super or C for anything else. Super will not punish the whiffed point blank move and Rook even gets hit in his armoured arms if he tries to do this.
Jaina: b+A to punish point blank, Super or C for anything else
Geiger: f+A to punish point blank, C for anything else. Geiger shouldn’t mash super for point blank, it finishes right next to Setsuki and she kicks him in the face.
My advice is to use B with caution and use this with extreme caution against Rook and Grave because those are already difficult matchups and this is a risky mixup that you should only really be using when you have a good life lead.