I'm on that list of most generous merit-givers, but I'm not a merit source.  It just happened that I was legendary when the merit system was started, and I'm also on the top-merited member list as well, AND I've given all of my sMerits away so far--so I ended up with a lot of sMerits from the airdrop in January and from other members, and because I didn't hoard them I could be mistaken for a merit source.  It isn't so.

Therefore, from that list you can't tell who's a merit source with 100% certainty.  I would suspect that most of them are, but who knows.
Yeah, I'm trying.