Now, is it destroyer or cruiser sized? I'm pretty sure it's too small to be a capital.
It appears that the sprite for the liner is ~10.5 times longer and 4.5-5 times wider than the sprite for the Talon. This suggests a sprite which is about 250 by 108-120 (27000-30000 pixels total). Average destroyer sprite dimensions are ~113 (min 80, max 140, std dev ~18) by ~185 (min 136, max 260, std dev ~39), with an average total pixels in sprite (including empty space) of ~20000 (min 15000, max 28080, std dev ~3600); average cruiser sprite dimensions are 169 (min 128, max 220, std dev ~33) by ~232 (min 180, max 280, std dev ~37), with an average total pixels in sprite (including empty space) of ~38000 (min 35000, max 47600, std dev ~4000). This suggests to me that the liner is a large destroyer, though it's not that far out of line for being a small cruiser.
If that center-forward dark patch with a lit area at the back is a flight deck, then I'm inclined to say that the ship is a cruiser for the simple reason that the size of that patch relative to the rest of the vessel seems to me as though it's too small for a destroyer-scale flight deck (the exit for the Condor's flight deck is about a quarter the length and a quarter the width of the ship, and the Gemini's flight deck appears to take up a considerable portion of the forward section of the vessel given that fighters can launch from or land at four points on three sides of that section).
If we consider the black rectangular markings on the vessel to be windows, then I'm inclined to say that the liner is a destroyer because the 'windows' appear to be too large for a cruiser; the Apogee, Heron, Eagle, and Falcon all appear to have windows at various points on the hull (Apogee on an apparently-raised portion of the front section about where the bridge of a Federation ship from Star Trek would be, Eagle/Falcon/Heron on a raised portion towards the rear of the ship about where Star Destroyers had their command towers), but the windows on these sprites are significantly smaller than the windows on the liner appear to be.
If we consider the ships which already exist, then there's already a ship in the destroyer-scale personnel carrier slot (the Valkyrie) and cruisers are completely lacking in truly civilian vessels (and in my opinion also in militarized civilian vessels; I regard the Venture more as a demilitarized warship than a militarized civilian vessel), which would suggest that a new vessel might for the sake of diversity be placed into the cruiser lineup rather than the destroyer lineup. However, multiple ships in the same role in the same size class while the next size class up is completely lacking ships of this role would not be unique, what with there being four dedicated destroyer-scale freighters and arguably two destroyer-scale militarized freighters (I personally am inclined to regard the present form of the Gemini as a purpose-built escort carrier that happens to have enough cargo capacity to make it a potentially-worthwhile freighter rather than as a militarized freighter that has a flight deck, but I know that the game description and classification, and probably some members of the forums, don't agree with me) and no cruiser-scale freighters at all (unless you really, really want to stretch for the Venture and maybe Apogee).
Overall, I'm inclined to believe that the liner belongs to the destroyer lineup rather than the cruiser lineup. Knowing that the liner definitely had a flight deck rather than basing the assumption that it has a flight deck off of the presence of that dark patch with a lit area towards the back would be sufficient to change my inclination from destroyer to cruiser.