Not your answer but in sea salt, iodine is present only in negligible amounts.

Im not sure chemically if theoretically a certain quantity of iodine could somehow influence the extraction. Personally I always look for pure sea salt (without added iodine) to be sure, but I can say ive used iodine-containing salt in harmala extraction and noticed no difference at all... I dont know how generalizable is that experience, how variable iodine amount in salt is in different countries, but I have a feeling it would be fine... Maybe another chem expert can give their opinion.

I would be more worried about other things such as anti-caking agents and other things added to some salt. I remember reading one anti-caking agent might react in certain extracton conditions, but I would have to go back to some sources to read what exactly was the issue.