Diego's animations are pretty jank in general, same with NiCO's. It can make the match-ups annoying for reacting to stuff. Doesn't help matters that that Diego move is a +19 GB that guarantees launchers.
Something that powerful should not be so visually indistinguishable, either have it only at the end of a string or give it very distinct animation, or just make it a high or something
and yeah it's slow and has crap range, but it's short range means it's used at the same range as his 5p/6p, so it's not impossible to incorporate this into his cqc game
You can still react defensive with a side step or hold. Now if you're talking meaty, then yeah, good luck. I'm assuming you mean reacting with an attack? Yeah, I don't tend to make that a reaction as it's easy to get yourself mixed up and counter hitted by him.
It's not a move you have to suddenly react when he has an uncharged one that's i16 and +6 on block. Especially if he's plus after a GB. Diego can just toss in 236P uncharged every single time if that's the case.
If you mean react into holding it, that's not an option you should go for. Fuzzy/jab is one, you can however step react it. Do not hold it, even bladez will tell you that.
The charged one is i35, in neutral situation you can react to it, but why would you go for the option to react and hold it when he has an uncharged version which makes Diego + thus making you lose your turn. Gotta fuzzy / step the options. If you try to hold it then uh oh, you are going to get hit and he pretty much earned that.
However if the uncharged one was not advantage, then the player who only go for the fully charged 236P, thus making it a true attack to -react- to because why would the player go for the uncharged one? this forces a player to only use it charged and making the situation obvious = reacting even off neutral or + frames.