I remember playing Tachyon and it was more a Wing Commander kind of game than a Privateer one. There was no trading apart from buying new weapons, or at least I remember it being so. Am I wrong?
Going by the description (haven't played it), you are not wrong. Look like it's more free form than the Wing Commander/X-Wing template in that you can choose missions and upgrade your ship any way you want, but it's not a free trader like Elite/Privateer. So it should be in the standard space combat group instead.