That's centanly one interpitation. However, the information is being provided by Spock during the mind meld. Calling him "Last of the Romulan Empire" wpuld be like referring to Checkov as "Czar of all the Russias". He may have called himself that but it's not relavent to the point Spock was making.
Old Spock was reporting the fact that's what Nero believed himself to be the last of Romulus, but--well, here we come to the ambiguities of telepathic communication as represented in film. What else was he telling Young Kirk? He may have been identifying Nero's belief as a rage-filled delusion as much as an accurate representation of the facts. Don't forget that, despite Vulcan's millennial existence as an interstellar power with multiple holdings, Young Spock said that there were only a few tens of thousands of Vulcans left. I'd prefer not to imagine how people surviving such locally overpowering disasters would be thinking, or what they'd be saying.
And don't forget that, all indications from the language everyone uses aside, the Vulcans and Romulans actually belong to the same species ...
Seeing as the Hobus Star was a fair distance away from Romulus and still managed to utterly destroy the planet it stands to reason that the otherRomulan colonies, particulary those older and more established ones, would be destroyed as well.
I don't think this holds. I've found a high-quality copy of the Star Trek Atlas map
. Let's say that Hobus exploded near the centre of the empire, around Beta Reticuli. Assuming the wavefront of Hobus expanded in a circular fashion, by the time Romulus was destroyed a sizable chunk of Federation space would also have been vapourized, including most of the Federation's Neutral Zone outposts, at least a couple of starbases, a few settled border worlds, and not far at all from Federation core worlds like Earth, Vulcan, Alpha Centauri, and Bolarus. It might even have gotten into the Klingon Empire's nearer regions.
If the disaster was that big, a lot of the reaction to the Hobus catastrophe strikes me as ... off. Why would the Federation have been in a position to dispatch medical ships to the space of Romulus? It would seem to make more sense to care to its own wounds, especially, if Romulus had been vapourized.
The threat was described as being specifically one to Romulus
, not the RSE. To me, it would make more sense to place Hobus somewhere in the "western" end of the RSE's ellipse, near enough to Romulus to destroy it but not so far away as to destroy significantly large volumes of non-Romulan space?
How many Romulan colonies have been mentioned before anyway? Perhaps the Romulans have captive planets but very few that they've colonized themselves.
In the filmed material, maybe, but the same could be said about Klingons, or Ferengi, or every other non-human species but the Cardassians. Colony worlds, as distinguished from conquered worlds, haven't been distinguished. This lack of distinction doesn't mean that they don't exist, any more than they do exist.
The idea that there wouldn't be large, populous, Romulan colonies, strikes me as unlucky. As much as the humans, the Romulans are an expansionistic culture, and the idea that in a history of starlight several times' longer than humanity's they wouldn't have founded a substantial number of populous colonies strikes me as unlikely. There's plenty of unpopulated worlds suitable for colonization in Federation space. Why wouldn't that also be true in Romulan space? And why wouldn't the racist Romulans preempt the expansion of subject species (well, maybe not as labourers) onto these worlds?
Even if all of the RSE's worlds were
conquered worlds with Romulan minorities there would still be huge numbers of Romulans absolutely. Towards the end of its existence, whites maintained Rhodesia
despite being outnumbered twenty-to-one by their subjects. The Romulans were able to control them before, and the destruction of their homeworld wouldn't do much to make the colonials less bloody-minded.