Two options:
1. Those are the central banks probing how weak is the bitcoin network (and it's pretty weak, can make it crash with less than a 100k)
2. He was sending the payments to himself
Gave them out seemingly at random.
Whatever the case they really got some attention.
It seems he really didn't care who was getting them. It was not at all like "Your comment was informative and I enjoyed it, here have this as a reward". Some of the comments just said "Thanks" or "lol" and they got $100.
