And reflexively, my posts cease to be available to the twit. Effectively, the twit is shunned.
No, I can't agree with removing another person's ability to read your posts. Removing their ability to reply, maybe. But not make them invisible.

I'd also like bidirectional transparancy on who's being shunned by, and who is shunning, whom. That's IMO useful information.
I'm still waffling on this one. On the one hand, yes, it's interesting information. On the other hand, however, it could lead to personally targetted vendettas and the like. Let people make up their own minds on who's shunworthy.

Scott's lead me to undersand that the "mark read" functionality may not accurately reflect the state of a fourm modulo twiti filter settings.
That should read "will not accurately reflect"; if someone you have shunned has posted, you would still see an LRPD. :-)