Squeak: I’ll take a look. The fact stands, though, that you need a Makor that playing ball is inherently Chillul Shabbos (and that ping pong counts as playing with a ball; the potential Chilukim are obvious). I would still assume that it constituted Chillul Shabbos because there was no Eruv, it was Muktzah, it was an Ashvuyei Gumos situation, etc.
I still don’t think you can claim “Not Shabbos-dik” to be Oseir here. 301:2 didn’t disappear.
And DY: Uvdin D’chol has to have some sort of potential Chillul Shabbos connected to it. So until you can find a potential Chillul Shabbos in ping pong (and the ball breaking isn’t it, for several reasons; though I could hear the Ta’ana that playing with a cracked ball is), I can’t see a reason that would be Oseir.