Face it, the supernova aspect of the plot of Trek 11 was the single greatest plot hole of all time.
That's not a dig at the film or if it was good/bad, it's just a factual rational assessment.
It's a huge gaping plot hole you could fly a Dsyon sphere through with room to spare.
I mean, apparently one star went nova and then just... what? Continued? Caused chain reaction? Expanded exponentially?
And if Spock had time to speak w/the Romulan leadership, then go home to Vulcan, talk to their leaders, who then decide not to help, and then hatch a plan with Picard and Data and Geordi (according to 'Countdown' comic) and what not...
...Seriously, the Romulan government wouldn't have bothered any level of evacuation during the week or two or three all of that took?
And how would their not have been galactic panic at a single super-nova expanding exponentially or causing chain reaction novas?
Not to mention that if it was expanding as such or chain reacting, it would have reached the UFP or Klingons sooner or later, so why would Vulcan refuse to help?
For that matter, why would logical Vulcan refuse to make a great show of trust and empathy by stopping such? Whether or not Romulus is their enemy, it is illogical to allow life to be lost - especially on that scale - due to politics or any other reason. Especially when the ability to help requires so little as 1 person in 1 ship with 1 substance.
None of it makes any bit of sense.
Unless you need a plot for a film and don't care how you get from A to B.
Not the first time for Hollywood or Trek to do it, not the last.
Just the single biggest example of a plot hole in modern (and likely all of Trek) history.