How about the under arm ball by Trevor Chappell? That was a ****ty ball too, only difference being this got hit for six while that was not. And that gets accepted as against the spirit of cricket.
What is the count of pitches post which a ball exceeds the spirit?
That's... also obviously very different? I feel like you're being a bit obtuse here.
The difference between a bowled ball that is so bad it bounces twice and underarm bowling is that underarm bowling is
not bowling. That was a blatant loophole in the laws that was immediately fixed because no one had seriously considered the possibility that someone would basically not bowl (let's be real here, underarm bowling is not bowling) and the rules would "allow" it. Meanwhile the ball bouncing twice has been an accounted-for scenario for many years now. It's not even the first time this has happened; I distinctly remember Jonathan Trott doing something quite similar, and the Allan Border example has been discussed before. Hafeez tried quite legitimately to bowl the ball normally, the ball slipped out of his hand by mistake and ended up pitching way, way short of where he intended, so much so that it bounce twice. Warner, seeing a terrible ball that he could hit for six, tried to hit it for six. It's just not at all the same thing.
Where I could see it being dodgier is if Warner had to basically run off the pitch to hit the ball because then the fielders are potentially in danger from a batsman running around swinging a cricket bat. But that's not what happened. It would be like saying that when big floaty full tosses shouldn't be hit.
For me the "spirit of cricket" balance is simple: if there's something that, if we
could outlaw then we probably should, but we don't because it would create other problems that are even bigger than the original problem being solved. "Ball pitched so short it bounced twice" is quite clearly not one of those scenarios.