Nothing connected there as far as I can see.
1) no mass merit. (Your title is incorrect)
2) The posts I looked at are not shitposts and in my opinion justify the merit they got. (I can understand why the user merited them)
Sending and receiving of merit is by no means "evidence" of anything. Users often read the same threads, speak the same language, are online around the same time and have the same interests.
3) Theyoungmillionaire is one of THE top posters on bitcointalk -
https://bitcointalk.org/index.php?action=merit;stats=topusersatThere would be no incentive for him to abuse the merit system. He has far more merit than he needs for ranking up. (His activity needs to catch up before he can rank up)
I very much doubt they are related - it looks like normal merit activity.
4) There is a thread for reporting merit abuse
https://bitcointalk.org/index.php?topic=2896910.0 - no need to make a new one.
OP - the best way to fight merit abuse is to make good posts yourself like the one you got merit for.
As the airdropped sMerits run out the merits will be coming through the merit source channels and from users that got merit for good posts.
It will become increasingly hard for merit abusers to cheat the system.
Others will see what is considered a "good post" and either start following good examples or not rank up.