I've never tried seaweed in fermented foods but it sounds a good idea.
Recently we worked on the development of a very nutritive sweet-and-sour food using shiitake mushroom and wakame sea weed (plus carrots and sesame seeds) and also one of our students developed an interesting pineapple marmelade with wakame seaweed.
Seaweeds like wakame and mushrooms like shiitake are not commonly eaten in Costa Rica and actually most people do not even know them. So we are now developing foods containing them but taking into account sensorial preferences of Costa Ricans. That has been a tough work.
I too feel it is a good idea. However, one of the important element found in most of seaweeds (which are mostly algae) is iodine. I would not be surprised if the fermentation does not proceed as hypothesized.
Absolutely a beautiful thought. But, I have health concerns. It should be taken into consideration whether there is pollution in the region where this source will be used as raw material. Especially if there is a risk in terms of heavy metal should be examined. When I think of seas and oceans, these resources should definitely be evaluated. For this, the processing methods like as fermented foods should be developed.