Yeah, I can see Rescue Breaths as possible and worth a try. Not chest compressions in the water.
Rescue breathing is routinely taught in Rescue classes, and is a real pain to perform. (Not much fun if you're the "victim," either.) I think some on ScubaBoard advocate just getting the victim to shore ASAP, but it might depend on distance. Probably worth at least a couple of breaths regardless, in case it's a near-drowning.
Sometimes people use CPR to mean the beginning of the assessment all the way through chest compressions, lumping rescue breaths as part of CPR.
This is very curious. Sounds like they were practicing/demonstrating either sharing air or regulator recovery. Trying that at 70' in an openwater certification class violates standards. Most likely the press report is wrong. Perhaps, though, it was a tech class and they were switching gases? (I'm not a tech diver, other than back in the dark ages my OW included decompression training....)