Circling minima are there for a reason. If you have commenced (i.e. crossed the FAF) an instrument spproach procedure, you can’t just “break off” and do a visual approach to another runway. This is called a circling approach and certain rules are required to be adhered to.
Just a hypothetical question... How low were you willing to go on the RNAV approach before you would have to have the runway in sight for the visual approach?