Gambling addiction operates on the same mechanism as MMO addiction. Given what we know about behavioral psychology, it's not logical to regulate gambling, but not MMOs.
The LARP companies don't have the money for lobbyists.
Uh, except LARPs are legal and gambling isn't... ?
As far as I can tell, the point of the grandparent is that "professional and amateur sports organizations" (as mentioned in the article) have money to lobby against online gambling, but LARPers don't have money to lobby against WoW(?)
Hey now, my beloved World of Warcraft is not a "lightning bolt! lightning bolt!" LARP.
Don't expect the law to reflect a consistent logical system any time soon.