there are 2 possibilities with that post.
1. He attacks the Dead Linger
2. Sergey attacks the dayz community cause he found a post where some people said "better zombie game than War Z"
either way he never clarified what it was after he started that flamepost, so defo troll behaviour. And next to some lol posts that only read Sergeys post. There are also people thanking sergey for bringing the game up to their attention. As that pre alpha footage resulted gave some people interested in the developement. And later in that post you will find some good footage.