I'm not going to psychoanalyse the brain parasite, but I imagine that the reason to do it could be as petty as shadow banning people with Fediverse (e.g. mastodon) handles in their bios shortly after he took over.
Only signal.me links were blocked as far as I understood. Other signal links kept working. (I have no first hand knowledge as I left Twitter when the owner changed)
Unrelated most likely, signal.me is a legitimate ___domain used by Signal. Doubt twitter is so on top of Threat Analysis when they fumbled their own redirects from twitter.com to x.com for a while.
Not really, the ___domain block was reportedly due to increased spam activity from that ___domain and performed automatically, so it would follow that a write up would come a few days later. That is if they are related, which is not a given.
It’s still a social media platform, not every action taken is some nebulous part of Musks agenda. Odds are there was an influx of posts that qualify as spam from the signal.me ___domain that were marked by an automatic system as spam, because they were. Suggesting otherwise is baseless speculation.
Given that Musk has deliberately blocked links to whole other domains before for extremely petty reasons, I don't see why we should give him the benefit of the doubt.