At best it's a ploy to attempt to destabilize and conquer what had already been built. At worst it's an attempt to outright destroy their competition from the inside.
It can't be ignored. It's outlined in the thread privacy policy that any form of interaction with one of their posts, be it upvoting, boosting or commenting, will allow them to create a surveillance profile for your account, and let them associate it with other Facebook/Instagram/WhatsApp data they might already have and use it to serve you ads and 'personalised content'.
Their policies are contagious, meaning that for example if kbin defederates from threads, but lemmy.world doesn't and they can still see each other, meta can still gather information about you because your posts reach them through lemmy.world.
Fediverse must absolutely block threads and every instance that doesn't defederate from meta.
May be naive and optimistic of me, but given that Threads has such a narrow focus, that being short text posts or "microblogging", I'd say it already greatly pales in comparison to the wider array of federated web apps.
Like, there's Pixelfed (Insta-like), Lemmy & Kbin (Reddit-likes), PeerTube (YouTube-like), Owncast (Twitch/Kick-like), Friendica/Hubzilla/Diaspora (Facebook-like?), Funkwhale (Spotify/SoundCloud-like?), Bookwyrm (Goodreads-like), WriteFreely (Medium-like), and uh...The list just goes on and on. There's so much more than just microblogging built on ActivityPub, and even totally different protocols that enable federation (Diaspora & Hubzilla aren't built strictly with ActivityPub, for instance, though certain elements may interface using it).
Tbh I see Threads as more likely to run a rather strict allow list of which sites they federate with, rather than ever openly federating, simply as a means to control the user experience and limit their liability for what their users may be exposed to (I know, that probably sound silly given their track record of exposing folks to awful shit, but they can't let women's nipples be seen!).
Instantly, as in the nanosecond they enable their ability to federate. If there's a way we can introduce actual fire and torches to that process somehow, all the better.
Immediatly just under every post "Switch to any other lemmy instance, for better experience!" And what would threads do? ban them all? Why not just let them defederate and because there is not so many registration restriction you can easily create new one and repeat.
You can defend your home by increasing security measures like alarms, cameras, and locks, creating a survival kit with essential supplies, developing an evacuation plan, and possibly investing in self-defense training. Always follow local laws and regulations regarding home defense.
This will bring some more potential users who, without threads, would never know that fediverse existed.
Then they will surely start adding features that mastadon/lemmy/etc don't have and it will be the time to pull the plug and defederate them.
Highly doubt that it will bring any harm to mastadon, for example, simply because their userbase does not care about meta crap, but in exchange it will get them some users for free for sure.
What's the quality of users that would come in via a company notorious for privacy violations? If you're signing up for this Threads in the face of the publicity around that sort of thing, you're a special sort of stupid.
Well, this is manageable by mods and mini instances etc. More people = more popularity = more good people and more bad people. That's at least what I hope. :)