I have to admit I am somewhat confused my #mastodon 's model.  If I follow someone, and they boost some post from an instance that is blocked by this instance, I just see nothing.  I would have expected some "post blocked by site admin" message or something instead of the post in the timeline.  Seems like only option to not miss (not see, but know the posts/boosts even exist) is to register on their instance?  Because it seems that following here (I can, their account is accessible), does not fulfill that goal.  Am I missing anything? 

 @3a2b67a3 If instance A "suspends" instance B, the effect is always mutual. Users on both instances will not be able to see their content or follow each other.

If they just "limit" instance B, 
users on both instances can still follow each other. Only then users will see content from followers.

This is how Mastodon works.