This strikes at the heart of what makes Mom test questions so difficult… every bone in our sales body says, “please say yes!”
The interesting insight is the Mom test questions are in themselves a great sales technique. I’ve sold more product by getting people to walk through and feel previous frustrations than by insisting they try it.
In your case, you might wait until the end of the interview and drop in lightly a one-sentence description of what you do (check out my essay on that). And then, wait to see if that proactively ask to be signed up. If they don’t ask proactively, consider questions that come in from the side… “when would be the most useful moment to try this product?” or “who would this be most useful for?” Again, “later” and “someone else” are opportunities to get curious again.