That and it's an AU ship... let's stick to OT and EU ships please.
If by AU you mean Alternate Universe, you're wrong it's not, it's canon. The Ghost is in fact canon from the GCW period, so it's completely appropriate to put it into the game in terms of theme.
Which isn't a good enough of a reason itself to do it. But the above quote is not even a remotely good reason to not include it, even if the poster was correct.
I do mean Alternate Universe; it's basically the same as the Star Trek reboot in that respect. The new Disney stuff and the 30ish years of EU stuff do not belong to the same continuity, and thus is a different canon. This is true regardless of whether or not it has some sort of official stuff.
The Disney universe is an alternate canon to the Extended Universe, and is thus the Alternate Universe.
It is a valid reason for them not to include it, assuming you prefer the old EU canon to the new, weird AU canon.
Canon. You keep using that word. I do not think it means what you think it means.