You can have reactivity without "bounce". If that's implied, then they really need to change the name of it. I think half the problem technically is people are just throwing words around without pinning down what they really mean.
And by the way, force alone doesn't produce actual work.
In some cases you can relate force to work ("this return force ratio *might* produce bounce in some guns"), but good luck crafting a rule where it is both effective *and* doesn't unnecessarily rule out certain configurations. Some guns will RT at 850PSI or less, some will never RT at all.
I don't see a feedback path so it wouldn't be considered "reactive". It's just "a really light trigger". Whether or not it gets banned is, again, a matter up to the fickle, inconsistent minded rulemakers. It's a good litmus test to see what the spirit of the rulemakers really is.
OK, so this I think is the unspoken heart of the matter, and where we separate the men from the bearded lady-men.
The mech question isn't about ROF, because you could just limit ROF and call it a day.
It's not about paint limit because you could just limit paint and call it a day.
It's about game design.
You want to design games where choices have meaning.
In current open play, if you want to go hard, it's a pretty easy choice. Pick up an electro gun with an electro hopper, go hose people. The choice is so easy that it's meaningless.
But what if we were go around and kick everybody's crutches out from under them? "No batteries. Now what are you going to do?"
Now people have to start making equipment choices which actually mean something.
It is exactly the same thing as when a video game maker goes in and nerfs a certain aspect of the game when it becomes boringly overpowered. They nerf that, then everyone scrambles to find the next OP thing, and sometimes they wind up finding something that was even more powerful than the original thing that was nerfed.
That's when things get entertaining.