The trip involved the Romulans leading the Enterprise into the nearest trap they could find which happens to be a comet. Given how fast ships can be at FTL, it is just as possible that the FTL flight passed near a star system and the Romulans diverted to the comet to gain cover.
But therein lies the problem: if travel is fast enough to take you to a comet in a random nearby star system, it is fast enough that the comet cannot
act as a diversion: it would take just fractions of a second to go through the tail!
I for one took this statement to mean that Romulans literally live on the surface of stars
Naah, the Commander was just anxious to see the popular girl band Pleiades and the stand-up comedian who does the superb Sarek impression.
See the Excelsior from "The Undiscovered Country" and Enterprise from "Where No Man Has Gone Before".
did not span an interstellar distance at impulse in ST6. The Enterprise
in turn spanned a distance explicitly established to be "a few light days" in "Where No Man Has Gone Before", again not interstellar. Indeed, in the latter case, it was also said that impulse drive cannot take the heroes back home at all, since even the nearest bases are "years" away.
A ship on impulse drive has never spanned an interstellar distance on screen. At most we have seen ships on impulse at the start and/or end of an interstellar journey, but we have massive precedent that this is what warp-capable ships routinely do when going from star to star anyway: they start out slow, they then do high warp, and they again slow down.
It is a different issue that ships credited with nothing but "impulse power" or "impulse engines" have gone interstellar off screen. What remains to be established is whether this crediting missed the fact that the ships in fact also
had warp drive.