Do you think Meta's Threads app will be beneficial or detrimental to the Fediverse?
Personally I believe that it'll make people associate the Fediverse with Threads, which is not a good thing. Edit: It'll replace their definition of the Fediverse, with Threads, and people may widely forget about Mastodon, Lemmy, Kbin etc.
When I draw from experience with Meta it will mean harm for the Fediverse. Their moderation will be bad. They won't ban Nazis. Nazis will attact marginalized people in the rest of the Fediverse. So instances will block Threats some won't = The fediverse is split. Zuck wins.
Why exactly do you believe that a partial mass-defederation of Threads would "split" the fediverse? That's not how interactions between instances works.
It's not a technical split, but an ethicsl split. Until recently the fediverse took pride in the fact that they watched out for eachother. If tgere was an instance that didn't moderate nazis, they defederated or at least muted it. Now, that the instance in question is run by a corporation with a history of bad moderation, desinforamation and hate-speech they get the benefit of doubt, because people think it's cool that an awful guy like Mark Zuckerberg sees a chance of making big money on their hobby. I think Meta joins the Fediverse to attack Twitter. It's a means to end competition. Thus they will not let the rest of the fediverse become competition.
"Competition is for losers" -- Peter Thiel
It's less than an ethical split, actually. If A does not federate Threads, but B does, Threads still does not meaningfully impact the experience of users on A. No defederation between A and B is needed for A to maintain their desired experience.
As such, there isn't a split. There's an ethical difference, but the impact is negligible, and thus it doesn't require disassociation, which would be what an "ethical split" would be.
Until recently the fediverse took pride in the fact that they watched out for eachother. If tgere was an instance that didn’t moderate nazis, they defederated or at least muted it.
Or if they were Beehaw, and the other instance got too big. lemmy.ml soft-blocked HTTP requests from the KbinBot. And so on and so forth. Add in all the drama that went down in Mastodon between instances. You're painting a very rosy picture of a tidy, well-behaved Fediverse when in reality it's been pretty messy.
Not that this is relevant, as mentioned above.
Now, that the instance in question is run by a corporation with a history of bad moderation, desinforamation and hate-speech they get the benefit of doubt, because (...)
Again, this isn't relevant in the context of causing a split. Let's assume Threads is full of Nazis. 100% of users are Nazis. No! 200% of Threads users are Nazis!
None of those Nazis will be able to get content onto A in the earlier example, at least not from within Threads. If A wants to block Threads, they can just do that. Blocklists don't have to be common between other instances, it literally doesn't matter.
Thus [Meta] will not let the rest of the fediverse become competition.
Meta does not have a way to impact Fediverse projects without the consent of the project they attempt to impact. They cannot "stop" Mastodon or Lemmy or Kbin in any way. It's FOSS.