So, let’s break it down.
1) You use a lot of ad hominem arguments — you’re good with tech, but a bit less with the art of  debating. Anyway, I’ve got no reason to doubt your story, even if honestly I don’t remember it. If it happened in a voice chat, well, I’ve got to admit my spoken English isn’t that great, and I can’t always translate exactly what I mean. In Italian we’ve got six or seven different words with subtle shades of meaning, while in English it’s basically just “cheat,” which kind of flattens everything out. The day you make the effort to speak my language, I’ll definitely be very forgiving about semantic mistakes.
2) I agree that changing DPI with a mouse button could be the real line between an optimized disc and a cheating disc. Without switching DPI on the fly, you’d be stuck at a DPI that’s too low to pull off the deadly moves that make it broken.
3) You actually brought up something really interesting, something I’ve been thinking about for a while: PHG is so unbalanced that Pred mains feel kind of morally justified in using every possible trick to try to close the gap. That’s where all the problems started, and it’s still the same today. Somehow, those brave few who still play Pred in privates feel legit using anything, without even seeing themselves as dishonest. -And let me say it for the fifth time: I’m mainly talking about the players I’ve RECENTLY played with in private matches -  In their minds, they’re just counterbalancing the situation. It’s a bit like Death Wish — instead of calling the cops, you take justice into your own hands. Psychologically, it makes sense. Ethically, it’s wrong. And in a way, I don’t even blame them.
That’s why I keep saying: we should just use the tools Illfonic gave us — the customizable settings. The real mystery is why nobody actually uses them. But hey, gamers are a weird bunch.