Nothing unusual. Check his registration date, seems that all the posts were deleted and that's why the activity went 0 but the merits are there. I guess it's a tradet account and the buyer is covering tracks by deleting old posts of the previous owner.
I don't think this is the case, actually. I don't see a single "received merit" when I check under their history. It seems that it was just a "bug" during the initial distribution of merit. When the system was released there were certain members that had their merit counts incorrect. It's possible that they just received an incorrect amount of merit to begin with. Deleting posts that have been merited does not cover up your tracks, it just keeps the merit stats and replaces it with "Deleted post" +1 or something. Do you have any proof this person has received a single merit?
Let me be more clear, I wrote my comment while I was waiting someone to pick me up, coz I forgot my keys, then he came and had no time for detailed explanation.
So, the account was a full member with all the activity and had the default amount of merit (100) for his rank.
Then the owner decide to delete all his posts and start all over. When your posts are deleted, you are loosing the activity generated by them.
The merit on the other hand, is something you cannot lose. So the default amount of 100 will remain even without any activity. There is no merit history, because he got the default merit back on 25 of January, when the system was introduced and he was a Full Member that time.
I hope now it's more clear