I see it as if your opponent calls safe, and executes a legal safe, then slops in a ball, he cannot continue shooting and passes control. You then do not (or should not, i feel) have the option to pass control back. Because your opponent called safe on the specified object ball (the lowest #ed ball), he would have to accidentally have made that ball for you to have the option of maintaining or conceding control. If he were to call the pocket and slop in another ball, then, idk. its up to if the rules were to be silly enough to give the non shooting player the option, or to allow the shooter to keep shooting. I think some ten ball tourney's rules are over complicated.