Many MMOs require or have required CC information to be put in before the end of the month, during the 30day game time. The pre-authorization of that high of an amount definitely seems like uncharted waters; typically it's something like a $1 charge if memory serves me right . Seems like they've at least responded to it.
This really is no different than many other services that offer X amount of days for free.
its completely different when they do a pre-charge, which can take up days to clear, meanwhile you are down 15 bucks or whatever your currency is, which you might need for something
I have never seen any game do this, and Ive played most mmos