Nice article -- great to awaken an awareness for that most innocuous of questions. It always surprises me when the answer is, "no, not right now". (I usually have a couple dozen questions to ask so my problem is the opposite: having to remember to interject "If you have a few more minutes just a couple more?"... but that is for another article!)
Not only is "no, not right now" a waste of a great opportunity to the "any more questions?" opening, the question is, as you say, a valuable selling opportunity. The fundamental sales concept "Always be closing" could not apply more than to job interviews.
Minor point: your context-less description needs, well, a bit of context--could not figure out how to parse your sentence: "These questions don't usually arise from the context of your interview, but you couldn't cover something you are pretty interested in at all."