An adult being hit in the knee is not a worse-case-scenario. Of course playing catch with a baseball in a public park also presents potential dangers. No disc is completely safe, it is more a matter of degree. I myself carry a CE Valkyrie.
From what I have read, it sounds like the PDGA informed Innova that the CE line was borderline in terms of rigidity. Innova therefore modified the plastic in response.
There may be examples of discs not officially banned that are too rigid. Probably the PDGA doesn't want to be too rigid (pun unintended) with disc manufacturers since our sport depends upon them. Other manufacturers may be less responsive to PDGA feedback than Innova. This is all conjecture on my part and this thread is about Dave's perspective not mine, so I think I better bow out.
Absence makes the heart grow fonder. Perhaps you are too in love with CE to look fairly at this issue