That's what I figured. And you probably have to commit to it, i.e. you can't hit confirm it? Because if you could, that would make Raiden's 50/50 safe.
You can hit confirm it, but you have to have insane reaction speed. For me personally, I put it at "Technically possible, but not very practical" in terms of a real match. Granted, I don't main Raiden, so maybe one of you crazy peeps would want to put the time into it to do it.
If so, here's a tip- don't react to the hit. By the time his first open handed hit connects, the window to A) process a hit versus a block and B) input the command for shocker is very small. It's much, MUCH easier to throw the B2, and then LOOK AT YOUR OPPONENT to see if their standing block animation is up. You have a decent window from when you start the B2 to do the cancel IF YOU SEE THE OPPONENT'S BLOCK ANIMATION. It starts as soon as the attack starts, so you don't really have to "hit confirm" technically.
Naturally, you'll cancel on hit if your opponent stops blocking or decides to low block at the last second, but watching the opponent's block animation was the only way I could practically cancel into shocker on block. Hope that helps.
