You could technically say that, but in practice, salt usually dissolves pretty readily when it hits food. Salt is also pretty invariably considered seasoning. You might see something like a sprinkling of sea salt on top of a truffle being called a garnish, and I'd say that's accurate, but generally, how much salt to add is discussed in the context of determining how well seasoned food is.
Of course, it's a fairly arbitrary distinction. The take-away, though, is that if you approach your food with "this food is bland, I should dump some horseradish on the plate to fix that," that's a problem of poorly seasoned food. If you approach it while cooking and say "I want to incorporate horseradish into this dish," then you're seasoning with it.
I typically don't add salt anyway unless I'm cooking with it. Sometimes I'll add the salt after for eggs. For a baked potato I'll use way too much salt though.