The autumn of 1973 - especially in the Southeast (US) - saw the biggest UFO flap I've ever known in that area. By mid-October the sightings, tales, and arguments had become a persistent, prolonged, and welcome respite from the wall-to-wall Watergate and Vietnam news. Lots of people got into the act as curious watch-keepers, serious lookouts, and yes, even outright pranksters and hoaxers.
Even in the Falkville area ... In his book (see above) Darnell writes that he and his brothers devised and perpetrated _two_ UFO-related pranks during that same period - one involving a foil-wrapped dummy and the other involving homemade illuminated balloons that were themselves reported in local newspapers as 'mystery UFO's / lights'.
If it was a hoax and Greenhaw wasn't in on it, I'd suspect other townsfolk ended up shunning him for being duped and making their fair burg look like a community of idiots. The more extreme - and conspiratorial - spin would involve the hoax being crafted specifically to humiliate Greenhaw and give the town an excuse to leverage him out of office.
If it was a hoax and Greenhaw was in on it, he could have been fired for that alone - regardless of any other grudges held against him.