Just because they won’t use Mastodon now, doesn’t mean they never will in the future. Especially when (not if) Mastodon sorts out some of their usability issues around signup and interacting with posts from other instances.
It would be nice to give them the option.
When you cut off a cancer, it dies. When you defederate a social network orders of magnitude larger and more powerful than you… it doesn’t even notice and continues to thrive.
This isn’t going to harm Threads or protect Lemmy.ml.