Good question. It may be because some of the biggest hashers are people who have an active interest in seeing MAX fail and are trying as hard as they can, perhaps mining at a loss, just to dump the price... and deliberately (and desperately) concentrating their mining power at 1GH to try and convince the community that a 51% attack might occur. This would be the only rational explanation in my opinion. And I suspect it is people like BitcoinExpress who is behind all of this. He has been trying to trash talk MaxCoin since day one.

See this thread for an example of the extent of the propaganda, lies and FUD BitcoinExpress is willing to go to:
https://bitcointalk.org/index.php?topic=553132.msg6045266#msg6045266