There are no terrestrial snakes native to Hawaii, and so there are severe restrictions in place to prevent their introduction. Introduction of any could have catastrophic impact on the native and unique fauna of the islands. This is why penalties are severe for having a pet snake or importing them (smuggling, in this case).
But I think that is a bit different from this case. A yellow bellied sea snake that washed up (such a natural introduction is not unheard of in Hawaii) has been rehabed and is on display at the aquarium. I think the interest of scientists in this snake might be high if it is really a snake, and I don't think the same rules would quite apply to the accidental acquisition of a seasnake that would have made it there on its own (the interest, I imagine, is that the banded snake eel -let alone a juvenile, would make it to Hawaii...if a juvenile, are they missing some sort of breeding population??).
The question, IMO, would basically be was the animal nonetheless collected properly with permits, etc...not so much if it was not what someone thought they were collecting, IMO.
It appears however there is a lot of confusion with the snake and the mimic snake eel. Most sea snakes, if I am not mistaken, have a compressed "oar like" tail which I do not believe is found in the snake eel.