You just disregard the red nav light and you go!! Captains are not supposed to be monkeys (unless they are payed peanuts and treated like in a zoo). Use your brain, of course a nav light is a nogo item but if you lose it after take off you will not turn back and do an emergency landing. That's why captains are paid for, be safe and help ops. That's what a good captain would do. Now if there is a flight controls or instruments or powerplant issue, a nogo item has to be taken seriously into consideration.