The problem with Bluesky isn't this random irrelevant design decision which might allow someone to pick a username which is offensive.
It is essentially another Threads. Another closed platform. This time with an air of exclusivity like the failed social network, Clubhouse.
We pretend it is something novel, because it was founded by a drug toting techbro who goes on meditative retreats, and because we have vague promises of "federation" and "crypto magic".
This whole project is a distraction.