Always check the dates of the last post! Lol. Welcome to the forum...

Genius Dale. 
Since this thread first passed on the first of its 9 lives... a new codex version has been published but I think even the one before had the first question around (I'm paraphrasing) "look dude, are you already managing this well enough with your prerequisite plan?"
You get the idea.
And the answer is "yes mate, yes I am".
I've worked in dairy and yes, antibiotic residues are a risk but I still wouldn't have it as a CCP. While we did intake testing for them, that was only verification of the controls around the raw milk suppliers. It wasn't accurate for some antibiotics but the farmers knew that if we found one out of spec they were paying for everyone else's milk which was a big disincentive. Same with temperature and pesticides. The incoming check isn't actually the control, it's verification of control in my view (if you're even checking the pesticides).
I'm trying to think of a situation where you had such little trust in your suppliers, and I can't help but think "get better suppliers".