@SleeplessOne1917 seems to be their GitHub handle. You can see this by going to one of the pull requests that are linked in the thread (e.g instance block feature)
@cannotsleep420 seems to be their lemmy handle. You can see this by going to the thread link the OP posted, in which that account is commenting about the UI tweaks.
Both accounts list their location as ‘Burgerland’(?) so they’re most likely the same dev. Plus the ‘SleeplessOne1917’ lemmy handle you linked has absolutely no activity.
You can also see @cannotsleep420 crossposting earlier lemmy changelogs that mention @SleeplessOne1917…
This is a bigger issue to leave it to users imo. Like lemm.ee admin said a few months ago, threads is too fucking big.
Anything they push on the fediverse will be what users see in All. Plus, popular stuff on threads is determined through Facebook’s algorithm, and it will also determine the fediverse recommendations by consequence.
The above is solvable if you block them I guess, but by default it will completely ruin everything.
However, lemmy 0.19 block feature doesn’t work on users of an instance, only posts hosted in an instance. Add to this that Facebook is a cancerous company making all its money from ads. Expect their bots to comment and make posts pushing ads on all instances.
All of this will also mean high workload on mods to regulate the content. Threads doesn’t bring anything good here, and defederation is probably the only way to protect us.