No he is not retired. He and Bear post there everyday. As for Eric he might have left JR temporarily because he was busy in something or to give chance to new staff moderators or something more important came up and Trailboss has moved him to retired staff. But later on Eric started posting again and that is why you see his post as your reply.
Moderators are all volunteers. Sometimes, life gets in the way, and someone feels they don't have time to spend doing all the stuff moderators do (you'd be surprised at everything that goes on - planning to take over the world takes TIME). They may feel they can't commit to doing that work anymore, so they occasionally remove themselves from that status - but they still participate on the ranch in forums.
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
As said above, some people want to be regular posters and not be staff. Eric is still a respected poster and chooses not to be active staff. I'm going to close this thread as there's nothing to be said on the matter.