Look I have been on both sides of the fence on that one - one friend disappeared for a very long time - but I knew she was moving, resettling, looking after all her kids, managing everything in her life - so I trusted she was okay and she came back, and it is just like that before.
I also disappeared because I shut down, and once in 2013 because I was in a bad way.
I don't think you can expect the moderators to do more work and do outreach, there is so much to running a site like this, that taking on more and more will only mean that it gets too unwieldly and too full on. People moderate as a service to our community - I think it is more appropriate to be grateful for what we have, rather than having ideas about asking for more from people, that is not sustainable.
I have a couple of emails of people offsite but mostly I contact everyone through the site. I trust that people will come back, mostly they do, though there is one I do worry about but she hasn't been here for the longest time. People come and go, just like in real life.