Always had a feeling that the band initially broke up due to political differences that may have surfaced, and Jason, one of Haughm's long time friends (and bassist in Agalloch) since school also broke off contact, which to me all came off as being very personal. I remember Jason, Don, and Aesop being vocal about anti-Trump in 2016 and Haughm was always quiet - not that there is anything wrong with not discussing your political views, but it just seemed odd with all the members that were vocal about it, and having a break up in the same year and doing so not on friendly terms, t, I am sure the break up in 2016 had something to do with a difference between them and Haughm with personal beliefs.
Sucks what happened to Agalloch because it had a pretty unique style - tracks like on Pale Folklore, with wolves and hounds howling and whimpering in the baccground, set to an acoustic guitar overlay in the forefround with dark black metal riffs in the background, you don't really hear this from any other bands and what made Agalloch stand on its own. I actually like Pillorian's debut album - it was a safe black metal album but very well executed with an obvious tinge of Agalloch's atmosphere. I was even at Pillorian's debut 2017 European tour, got a shirt from it too which I like.
Generally I don't care too much about a band member's political views, since I listen to the band as a standalone entity and have never obsessed about individual artists in music - I mean if I did I wouldn't be able to listen to Deströyer 666 which is a fantastic band even if K. K. Warslut is a piece of shit. If they do dumb shit in public and they're scorned or have to face consequences, so be it, that deserve it then, like Haughm does now.