lemmy.world and sh.itjust.works both are basically a free-for-all to signup, and they were dealing with heavily increased amounts of trolls from those instances. They are currently in talks with the admins/mods of those instances to try to rectify the problem and re-federate, but to keep beehaw a safe space, where losers can't walk in off the street and acost their userbase, they needed to remove federation from these instances.

There are only a handful of full-time admin/mods for beehaw and they don't do this for a living, this is something they do on the side, for no pay. It is not in their best interest nor the best interest of the users to let hundreds of new accounts from an entirely different instance run roughshod over their server.

It is entirely reasonable. The user above will not "control their own experience" until they have started their own instance. How long until the admins they're currently under make a decision they don't like at u.fail? Who knows, could be days, could be years, but the thing is: it's likely.