@aaronkurz
but if you find it annoying that things from threads.net pop up in your feed...I know of a way to get rid of it.
Select the three dots on the post, the "..." then select "block domain threads.net".
That will block everything from threads.net on your account. That way if it irritates you that they don't federate then you won't see their stuff.
The only problem is gonna be if they choose to federate in the future, then you'll have to unblock them.
Personally I just blocked the entire domain. I'll read in the news, which I check from time to time about Mastodon growth, if they federate with us and then I"ll unblock.