Ok, I sent a message - without a link to this post, which might have offended him.
Polite? Judge for yourself; this is what I wrote:
I’ve noticed that you have closed quite a few bugs which affect EOL Ubuntu versions. Thanks a lot for your work with that!
However, please note that even if a bug reporter used a specific Ubuntu version when reporting an issue, the issue is not necessarily specific to that version. And if not, the bug should not be closed solely due to that version reaching EOL.
I think that https://launchpad.net/bugs/1676977 is an example of a bug which you closed gratuitously. In that case the OP objected, but then you were gone…
So please be more attentive in this respect. If you don’t know that the issue has been fixed in later versions, at least subscribe to the bug report so you see if the bug reporter or someone else has something to say.
Personally I think there is a nicer way to handle some of those bugs: In the comment you can ask if the issue is still present in the latest Ubuntu version, and mark it as “incomplete” instead of “invalid”. That way, if nobody reacts, the bug will be automatically closed later on.