http://u.qdnx.org/file/rozzin-20160212T030126-9u2k7hs.html
Interestingly..., looking at the !gnusocial commit logs and online conversation, it looks like @mmn actually did make notice-deletes propagate through the network quasi-recently: http://status.hackerposse.com/conversation/87921#notice-87928 (commit from Sat Oct 10 11:08:17 2015 +0200: "I think I have made the delete verb generate proper AS").