hello99, see the very next siman, 463, where it’s clear that even sea salt is OK if it’s only the small amount that one would put in cookies.
Bichlal, the distinction between sea salt and rock salt doesn’t make sense; it’s exactly the same substance. All salt is originally sea salt, it’s just that some of it dried up hundreds or thousands of years ago when the sea receded and the area became land. It’s all NaCl, and has exactly the same effect. And this distinction is not something we received from Chazal; it seems (from the little I’ve seen) to be the Darkei Moshe’s own chidush, so we are not obliged to accept it if it’s neged hachush.