This 'registry' is an alternative to having saltwater fishing licenses.
Something many people are not too thrilled about, but it's going to happen whether they like it or not
If coastal states currently without saltwater licenses fail to implement one by the deadline, they loose the revenue of local license sales to the feds.

Personally (and selfishly) I'd like to see the states procrastinate as long as they like
I regularly fish the coastal waters of 4 states, Mass, CT, NY, RI. and I will often will kayak between CT, NY, and RI waters all in the same day.
I wouldn't be too pleased about have to buy multiple licenses just to fish what I consider my home water