I've done this multiple times. Going to "Manage Manual Bills and Income" or Tools > "Bill and Income Reminders," if it shows a "Schedule These" suggestion at the bottom of the "All Bills & Deposits" tab and I REJECT that suggestion (either by right-clicking on it and selecting "Reject" or by going over to the Action column and selecting "No"), I get a dialog box saying "Quicken will no longer automatically suggest that you schedule [that bill]." It then promptly schedules it anyway. If I delete that now-scheduled bill, it continues to suggest scheduling it and the process repeats.
I've reported this from within Quicken, but thought I'd brighten other people's days with the report.