This is a bit of a problem, I agree. Not sure if there's an easy fix as Joe mentions. I have a number of sites where a main menu button isn't clickable but the child pages are. Ideally on mobile you could click and expand a non-clickable menu, but it wouldn't navigate to a page.
What I do as a work around is replicate the child page navigation on that non-clickable page. That way in mobile you just see a simple page menu (could use child menu module). This actually works fine. It's a little extra work, but gets the job done.