The supernova being Romulus's own star would solve a few problems, but it would just raise others. Not the least of which being that Spock's plan will basically fuck Romulus either way. I guess that explains why Nero is so pissed off at him (I would be too), but it turns Spock into a genocidal mass murderer. There's really no good
way to rationalize the supernova business.
There are things to like about Abrams Trek, but it takes scientific illiteracy to whole new levels.