The Friends of DTVA don't go airside for snow clearing duties, they take care of most if not all landside, this frees up more of the airport staff to focus on the more important airside areas.
DTVAirport - are you saying that airport staff alone don't have the capacity to clear snow from airside and landside and are in effect reliant on volunteers to do some of the work for them, particularly areas (ie landside) where airport management know the Dept of Transport would be less strict on security procedures ?