It depends. If they are choosing only to defederate specific instances, yes. If they are choosing only to federate with specific instances that leaves it up to you getting on the list by talking to those instance admins or something. If they are not federating at all then of course you're just out of luck.

Re. Beehaw: It's impossible to guess their intentions at this point. They are only defederating specific instances and have said they are doing so for specific reasons. As I said to someone else talking about this just as it happened:

(Originally comparing this to some of the instance blocking that happened back when I ran a Mastodon server)

Insular communities gonna insulate. Defederation has collateral damage, but among some communities that is acceptable because they view intolerance and the toleration of intolerance as close enough to warrant blanket handling. (See that “Nazi bar” story that’s often cited)

(Then talking about how that relates to lemmy Lemmy)

IMO moderation necessarily has to exist two places in a federated environement. Yes, the community (hosting instance) always has to do moderation, but so does the federating instance. If the federating instance does not have policies in place to handle bad actors who go to other servers and break their rules and it is a large enough problem this action could make sense even well into the future. Unfortunately Lemmy is in a quite early state so I don’t think the tooling to do such work well even really exists. Something like only allowing confirmed posters from federated instancea or requiring someone to be subscribed for an amount of time before posting could do wonders. Yes, this is the nuclear option, but their choices at the moment are a butter knife or a nuke.

I sincerely hope this gets better as Lemmy matures.