It's really sad to hear that happened to someone. Sleep apnea is indeed a surgery risk - that's why they have everyone checked out prior to ok'ing them for the procedure.
I have fairly severe apnea. On bi-pap pressures of 22/15. There's another side to Cpap/Bi-pap use after surgery, though, that needs to be mentioned.
1. Everyone needs to follow what their surgeon tells them they need to do. If that means bringing the machine to the hospital, that's what you do. No "tweaking" of surgeon's orders.
2. There is an inherent risk of breathing issues with anesthesia that are NOT related to sleep apnea. It's hard to judge based on a third-hand account, but it seems to me the anesthesia was more of the culprit here, not the presence or absence of the Cpap machine. Even with my severe apnea - I didn't have Cpap put on me immediately post-op. I was put on nasal cannula O2, and the respiratory tech came in later that night and set my machine up to have the O2 added to my Bi-pap mask. The hospital monitors vitals constantly, they should have/could have kept her on a ventilator to keep her breathing regulated - they worry about Cpap only after you've been cleared of other complications after surgery and it's clear you're in a regular recovery state. Sounds like there was some irresponsible decision-making going on, unrelated to Cpap.
3. There HAVE been cases where the Cpap-Bipap has caused physical problems with the pouch immediately post-op. Some people's pressures are so high (as with mine) - that air gets into the throat/esophagus, and the air has been known in some people to rupture the new internal sutures of the pouch. Check out the Sleep Apnea forum archives for more info on that. Not a problem for most people, but for some it can be an iissue. That's why it's so important for people to use their machine prior to surgery to get a feel for how their Cpap air flow behaves, they can discuss any concerns with their surgeon prior.
Even with my level of apnea, and the fact that I have to be on Bi-pap (not for comfort, but for necessity) - I did just fine with simple 02 immediately after surgery. You'll be on a ventilator during the surgery as normal procedure. Putting a C-pap mask on you, if the anesthesia is affecting your breathing, may not actually improve the situation - as I mentioned before, the responsible thing is to keep the patient on a ventilator and not take the chance on the apnea interrupting things. That's why you go to a recovery room until you wake up - they don't wheel you into your normal room until your vitals are stable and you've been 'roused from anesthesia. There may be more to the story than you heard, but in any case, it's very sad to hear.