Usage and Grammar

Q. Recently I was trying to determine (once again) whether subjects should be considered singular or plural when they are of the following form: rock(s). Personally, I think the simplest approach would be to treat it as any other parenthetical note within a sentence: it’s a note to the reader, but it should not affect the grammar of the sentence. Therefore, “rock(s)” would be treated as singular, not plural, and certainly not singular and plural. I looked through CMOS but could not find a solution. I guess my actual question is, is there a flaw in my reasoning, and if not, could Chicago recommend it?

A. The trick (used frequently in CMOS) is to use that construction only when it is not the subject of the sentence. Its use as the subject upsets us, and we try to avoid thinking about it. We prefer that you make up whatever rule you like. We are going to take an aspirin and lie down.