I can understand it most probably would be account strength in the hope of getting more merits for when he took the account to Legendary but why would he do it now when he is far from that goal?
I am not sure why that surprises you so much, that someone who is far away from Legendary rank (activity wise) wants to reach that 1k merit mark asap, or that he wants to keep farming merit. I mean, we all know more merit earned in 120 days often means better signature campaign so its only natural for account farmer to keep on farming merit in every possble way he can, and he became pretty decent at that.