My conclusion, chatting briefly with admin here I found out the inside of how this new thumbs up and thumbs down works. Which they said they will be doing a full roll out in the next few days.

Everyone can like / dislike a post once including their own. A email is sent to that user indicating if you liked or disliked their post. Most importantly a post shows on the board how many likes / dislikes it has. If a post has 1 like 1 dislike it will show as liked by default. So if someone dislikes your post 5 times all it needs is 5 likes to over turn it.

I think they nailed this imo, think about it, transparency at its best.