How can a GM have a post count greater than total posts count for that game when there are no players?

He might have deleted posts from the game.  They would still show as part of the total number of posts he has made, even thought they are no longer included in the number of posts currently in the game.

Huh, I thought that if a GM deleted posts it also deleted them from the GM total post count, guess not.  Thanks.

Nope, the player/GM count shows the total number of posts they've made in the history of the game, and can only increase (because even if they delete some, they still made them).

The post count for the game shows the current number in the game.