I'll happily join your crusade, but I might be useless... I'm not very knowledgeable about computer stuff. I'd like to be, though.
How does a client know someone muted/blocked someone else? Hmm. I guess the blocking must involve telling a relay to make an exception to its relaying... So if you wanted private mutes, wouldn't it just be a matter of only telling certain relays and those relays not relaying that?