Right now it's not even mastodon compatible let alone lemmy. There are some arguments on how federating with them will allow people to migrate to a more privacy respecting instance and still view threads content, and some users say this will allow them to still communicate with their friends who don't want to switch away from threads.
So while we do lean towards defederating from it, it's some months away before we need to actually decide and till then we are simply listening to and discussing both sides of the argument.
It depended on how you used reddit. They were extremely fast, had no ads, trackers or javascript so were extremely privacy friendly. But they were read only so you couldn't engage with the reddit content through them.