Interesting..., in that Advisory Circular that Bloggs found there is
"8. INFORMATION PROVIDED BY AERONAUTICAL ADVISORY STATIONS (UNICOM).
UNICOM stations may provide pilots, upon request, with weather information, wind direction, the recommended runway, or other necessary information. ..."
(note the word may)
and
"17. USE OF UNICOM FOR ATC PURPOSES. UNICOM SERVICE MAY BE USED FOR ATC PURPOSES, only under the following circumstances:
a. Revision to proposed departure time.
b. Takeoff, arrival, or flight plan cancellation time.
c. ATC clearance, provided arrangements are made between the ATC facility and the UNICOM licensee to handle such messages."
(note the lack of any traffic or separation information)
To my way of thinking, 'traffic' and or separation are ATC functions and therefor UNICOMs do not provide such functions, but I can interpret ", or other necessary information" in section 8 to mean that the UNICOM operator can/will/might/won't provide traffic and or separation.
ie. it's up to the UNICOM operator as to what information they want to provide.