I had a similar thought; that Essenes was the name taken by the ousted temple priests, or a name applied to them...
I’ve always understood that they where priests of the Maccabe tradition, versus, the Herodian appointed priests, so ‘ousted priests’ would fit.
Well, who we are going to believe, Flavius Josephus, who lived during this time or someone a few thousand years later with a degree......hmmmmm