... Starships have the ability to shrug off gravity, after all, and gravity is the only arrow in a black hole's quiver. Gravity, and gravity gradients aka tidal stresses. (And a fanatical devotion to... Sorry, wrong show.) Starships don't fight gravity simply by the power of their engines - they also have doodads aboard that actually negate gravity and laugh at it when it goes down. Thus, the very same thing that tears Vulcan asunder might have serious trouble harming a Romulan mining platform. Nero's death might be solely due to the damage his ship suffered from Spock's ramming attack and Kirk's later shots, and he would have simply moved to some other time and place through the hole unharmed if Kirk hadn't fired on him.
Timo Saloniemi
The Enterprise had a little difficulty shrugging off gravity and it was still capable of warp 4. I suspect the problem is that its a bit more tricky when a black hole appears
inside your ship, as opposed to the ship going through a wormhole once it has stabilised. Its not as though Nero just put on a couple of extra pounds, a developing internal black hole has got to stress any ship's "doodads". This would seem to tie in more with Kirk's remark about the Narada being too close to the singularity. Well you couldn't get much closer!
Of course if you want to advance a theory that implies nuKirk, nuSpock and the rest of the nuEnterprise's crew didn't know what they were talking about, I will happly commend your of integrity, even if I don't agree, on this occasion.
I just accept it as silly magical fantasy element, like the Genesis device or a big pink forcefield surrounding the galaxy.
The "Genesis device" and "the big pink forcefield" are not fantasy elements, in my view. Merely unexplained technology or phenomena. The difference is that while red matter is also unexplained technology, it is simply used to achieve impossible things, even given its purported properties. So if there is a fantasy element about red matter, its the way it is used, not its scientific validity (some leeway should be given concerning scientific advancement in SF after all).
I'll grant you, these things are examples of soft science fiction. But there is no indication they are
supposed to be seen as magical. I.e unexplainable scientifically even in principle. I don't think mere unlikeliness or lack to explanation (however annoying that may be) renders them fantasy. Who would have thought a thousand years ago there was a strange magnetic field surrounding the Earth for example. I'm not sure that being ridiculous in some way (implementation for example) renders them fantasy either mind you.
If that's the case, why try to stop the supernova with red matter if Romulus has already been destroyed?
Dunno. I guess Spock figured since he was there why not? Or maybe to save Remus?
That's a nice attempt at a catch. So Spock arrives just as Romulus is destroyed and has to deploy the red matter before Remus also buys the farm. No wonder he had "little time"!
Unfortunately here is where the ridiculous use of red matter alluded to above comes in. If the black hole is going to have any chance of containing the super nova it would have to immediately expand its event horizon to just beyond the super nova's wave front (at least in the direction of Remus). Even if that was an undocumented capability of red matter, it clearly doesn't happen because if it had Spock Prime would be dead as soon as it deployed (or maybe he would be on his way to the past, or both, who knows?). I.e. Producing the red matter black hole only served to allow Nero and Spock to travel to the past, nothing more.
*** Edit:
Hmmm, perhaps there might be enough time, a few seconds, perhaps a minute or so, to allow the red matter to deploy, so Spock can get out of the way at high warp. But that just creates more problems. Remus has, at least for a while, a truly massive black hole within a few light seconds. If tidal forces didn’t rip it apart it would probably fall in (Oops)*. And if Spock is that far from the black hole that he is out of its gravitational effect, how does he fall into it? Actually, how does anyone accidentally fall into a black hole anyway? What do you mean the Enterprise almost fell into one?
* Just as well red matter black holes aren't seen to work that way any how.