More to the point, are you suggesting these unicom operators will all be unpaid?
When I am flying I may not be being paid to provide "that information" but I am being paid to fly. I can't see anyone paying a person to only operate a unicom - if it is busy enough for that either a tower is required or a CAGRO would be more appropriate.
Using the example of YBHM (part time tower) it is very busy at times (busiest just after the tower closes) yet there are large periods of time where there is no traffic. During these periods other duties could be performed. The unicom does not have to be continuous - it could be started and stopped like YBHM tower which closes late afternoon and for lunch.
From a liability point of view as a pilot even though I am not paid for the information, if I gave dangerous or grossly negligent information I believe I could still be sued. Giving information to another person creates a duty of care to take reasonable care to provide that information.