Well, maybe.
Speaking ASA
If the umpire is offering a DNP signal because the batter is not in the box, 10.4.C notes that this is a suspension of play and the definition of "TIME" is a term for a suspension of play. So, could such a signal by the umpire be taken as a suspension of play? Yeah, it is a stretch, but I've seen folks take longer trips to sell a point.
All that aside, I agree with Steve's analogy of the situation and how it should be handled.