I respectfully disagree with you Peg. There is no possible way to prevent triggering everyone, that's just not realistic.
I do recall the time the "I'm leaving" posts were banned and I think Doc John handled that situation beautifully. In my opinion the posts were being used as attention seeking devices and manipulation tools. These types of posts were banned and situation solved.
If a person decides to leave, and they are in good standing, what logical reason would the site have from preventing them from returning? This is a support site. If I decide for whatever reason to close my account, then a week, month, or year later something happens and I need the support I found here again I should be denied that support because someone finds it annoying that I've closed my account? Where do we draw the line? What is the difference to you (generic) if I close my account or just not log on for three months? Should we then have a rule that if you don't log in once in a 30 day period my account is then closed for me? Some issues are our own and we just need to deal or use that blissful ignore button, in my opinion this is one of that situations.