I also seem to be missing the point of this, hence my "answers" may not be 100% what you'd expect. Also, with the risk to offend you (I hope not, though), this topic looks somewhat like "yet another Meta stats, fishing for merit". This being said, you
should expect some harsher replies.
Now, if you want to say that only the merit sources that have passed away deserve a "Rest in Peace", it's imho unfair. There are many people who have left the forum - some have passed away, about many we don't know - and clearly there are more who are being missed than only the few inactive merit sources.
Indeed, finding out the merit sources - especially by hand - is not an easy job, since most aren't boasting it. And only the numbers can be wrong, since it's not unexpected some (few?) merit sources don't care or have difficulties in spending the (extra) merit. It's a volunteer job (as you very well noted) hence we cannot blame them; an interesting fact is that some didn't even ask to become merit sources.
(The fact that some merit sources will not tell they're merit sources is because they can become targeted by merit beggars.)
I think that one point behind this topic was to make some sort of subset of
this list.
I think that another point behind this topic was to somehow induce that we need more merit sources - which
I knew it was the case about 1-2 years ago, but right now I really don't know (I don't say it's not the case, I really don't know). But if you think that you are fit for being a merit source... nothing stops you from applying to be one and let forum admin decide (when he will approve more merit sources, which I simply don't know when will happen)