The way I read that is;
If you have three start attempts OR have cranked the engine for 4 minutes, you must then wait 30 minutes before trying again.
I don't believe there is a limit to how long you crank the engine following a tailpipe fire etc so that 4 minutes is a minimum - if you have only cranked the engine for 3:59 you can attempt a second start straight away (obviously considering the first limitation of pauing for 15 seconds.)