That's the point. Hellfire is already catered for as explosive ordnance on the ship, it has an already developed launcher and is already in-service with the USN...RAM has an anti surface capability while Giffin, although less capable, is cheaper and is being developed to be compatable with the RAM launcher. The embarked Romeos, I assume will have Hellfire leaving the Griffin as a defence against swarms of light craft closer in.
All that has yet to be done for Griffin to obtain a less capable weapon, but then the USN says Griffin will only serve until 2016?
The whole thing is REALLY weird. If it's only till 2016 anyway, what's the point of adding ANY new weapon? RAM as you say has anti-surface capability as does the 57mm, the twin 30mm's, the 12.7mm and small arms that will be carried, as well as the Romeo or Fire Scout that will be carried...
If they only want a temporary solution and absolutely HAVE to have a missile capability then just have a contingent of USMC personnel with Javelin on-board and save some cash!
How much close-in anti-surface will they need over the next 3 years?