Airmonger

Someone who spreads empty talk, false rumors, or worthless air-based ideas; a dealer in insubstantial or false information.

From 'air' (as in worthless or empty) + 'monger' (one who deals in or promotes). The '-monger' suffix comes from Latin 'mangere' (to traffic), used in words like 'fishmonger.' 'Air' here means insubstantial or false.