I posted a medium-short summary elsewhere with a couple of links for folks looking for slightly more context.
I don't think the eris or defederation things are Huge News in themselves, but if it's true he doctored a screenshot to make the .art admin look bad, that's not a good look for a lead deve/flagship instance admin.
.art is an influential leader in community safety/moderation standards in the fediverse; their standards for federation are moderately high, and probably higher than folks on many lemmy instances would likely agree with. But it feels like the firefish guy has possibly a pattern of not doing his homework about things in general?
Obviously the big question is, did he actually doctor screenshots and if so, WTF, man.
Unsurprisingly given its extremely high profile as a purveyor of transphobic coverage, many mastodon instances have greeted them with a firm block. (If this confuses folks who don't pay attention to this sort of thing, just picture in your head if it was fox news.)