This post doesn’t address the main “pro-federation” point that I have seen. People who are support of federation aren’t saying that Facebook is a great company, they have great morales or that they aren’t supporting ActivityPub for their own gain. I think there is very little doubt that FB is a shit organization with no morales who thinks that this is a great move to get people back to their sites.
The most common reason that I see people supportive of Threads’ federation is that they believe it will help people move off of Facebook and other proprietary platforms onto more user-friendly ones. If all of your friends use Instagram it is very hard to move to Mastodon. If you want to stay in touch you will at least need two accounts. You can move friends but it is hard because they each need to make that switch and it affects their interaction with others, or they need to manage multiple accounts until most of their friends have switched. If your friends use Threads (and it federates) then you can switch to Mastodon with very little friction, you can still interact with all of your existing friends in more or less the same way. Similarly each friend can easily move without managing multiple accounts during the transition. If all instances have blocked threads.net many people just won’t move, they will stay with FB.
To make a good argument you need to either refute this perceived advantage or argue that it isn’t worth the downsides. Making up a strawman doesn’t convince anyone.