Considering the fact, that with punkbuster, I can decide what it will scan (by keeping a seperate system or seperate data) it feels way less invasive than a blood or urine test where I can not decide which information it will reveal about me. If I were pregnant, it will show. No way to opt out. If I have pictures of the unborn and I don't want them scanned by punkbuster, I don't copy them to my gaming system. I would even call that opt-in.
I don't have intimate knowledge of punkbuster. Not more than say Ebay or Amazon or Activision. All of those could use the data for illegal purposes. Yes, maybe there is some evil PB developer who is just now playing my Pirates savegame because the program scanned it and decided to steal (copyright infringe?) it. Somehow, the possibility of somebody misusing my credit card data seems more threatening.