Another way to look at it is that "timestamp" = "permalink", which is a fairly common pattern (I'm not trying to imply that it is intuitive, just that it is common). Once you are at the permalink you have a range of options available to you.
Same, as a permalink. I'll bookmark the permalink then run it through archive.org using a simple addons of mine, in case HN goes down I will have an archive backup.
Putting more stuff under the permalink page linked from a timestamp is a web tradition that's older than HN. I don't know if it's good, but I do notice when I can't click a timestamp. Even Twitter and Facebook abide it.