This question was re-opened today by msh210. When he re-opened it, the last content activity on the post had been an edit by me, a year ago. I noticed a few minutes later that it was listed on the front page as "23m ago Isaac Moses,"1 which seems to imply that I'd done something to it 23 minutes ago, which I hadn't.
I suggest that in this situation, one of the following should be displayed:
1 yr ago Isaac Moses - reflecting the time and author of the last content change.
23m ago msh210 - reflecting the time and author of the most recent activity that put it on the front page
23m ago - reflecting the time it got onto the front page and concealing who re-opened it
1. I'm sorry that I don't have a screenshot, and I can't show this state now because the question has since been edited.