Bloggs,
Dick has already trotted that furphy out before. As you have just now pointed out, and I have before, that is the ONLY instance of Unicoms delivering traffic that is mentioned in the entire FAA regs and AIM on the subject. They are quite prescribed and succinct on what they can and can't provide, and traffic is noticeably absent.
However, just one oft quoted instance in an example radio call...........
PS the example phraseology is for a taxing aircraft requesting traffic. This does not mean the Unicom is allowed to respond with it. There are no examples of what the Unicom operator should respond with, or what criteria they should apply when assessing it.