The only problem with it is you can't (or shouldn't) digest it.
Iodine is put in salt to make it safe for human consumption.
Non iodized salt is and has been, recommended for tanning for quite some time. The reason being; not only does it lack the iodine, but there are other chemicals added to iodized salt to prevent clumping, etc. which combined have been known to raise havic with PH levels, and white fur or hair on some hides.
For salt drying hides, and I don't mean tanning
either or is fine. The biggest concern would be to find something that is of a fine enough grade to do what it's being use for.