FS2 Retail Campaign Spoiler, since you obviously haven't played it. The ship appears there. I would suggest playing the FS2 campaign to learn what THAT is, it's much more fun that way... but if you don't want (which you should) or have no time (which you should get) to play through FS2 campaign...
Spoilsport.
Very well, if you insist... it's some incarnation of Shivan Sathanas Juggernaut. So you got pretty correct in your assumption, it's a very evil very hostile enemy ship. Can't tell if that's the original :v: model or HTL Sathy, though.
Now go play the FS2 campaign. And remember to keep spare shorts available at all times.
Don't know what it does in TBP core VP. Perhaps it's an Easter Egg, perhaps it's some remnant of some test or something... If no table uses it, it won't affect the game in any way, though.