You might be interested in https:// www. jwz.org /gruntle/ rbarip.html (I'm obfuscating the URL a bit because the website's owner does something rude if your browser sends an HN referer header)
I believe so but from what I recall, he still wanted syncing between phone/computer which required the messages be stored at some point, alebeit with an extremely small ttl (minutes? seconds?). This miniscule retention meant the record was created despite a low ttl and so when the record was removed, it became a violation of the court-ordered record retention. Again, this is all just from fuzzy memory but I think that's how it approximately went down.