Well, first off, there is no service as this capability doesn't exist. And perhaps the article got it wrong or missed some nuance, but it sounds like this is being done the wrong way in that they haven't figured out the CONOPS for it. The way it's supposed to work is that if a capability gap is identified in planning then you first look at other ways you can address the capability gap without developing a new platform. It didn't sound like that had been done. To that end I'd be curious if the gap is such and needs the development of a niche capability in a very unique aircraft. I think jmquate hit on the other limitations of these platforms in that they're heavily limited by sea state. It would seem that a CV-22 was bought to address these very issues (see Operation Eagle Claw). Oh, and you put a CV-22 on just about every major type of surface ship.
Also, developing a C-130 into a seaplane isn't an easy task. That's essentially making a new airplane. So it won't be cheap, easy, or fast. So it'll be an expensive and very niche platform. At some point that money is coming from somewhere else and DoD needs to ask if their RDTE is better spent on this or something for relevant.
But all that said, it's still a romantic idea because who doesn't want to SPECOPS Jimmy Buffett?