It's a difficult one, I grant you that. The problem being that if "timeship" refers to a ship that has the capability to travel in time... then we can't rule out that the Great Houses used any other ships to travel in time. It sounds stupid but we can't just jump to conclusions. "Timeship" is a generic term; "TARDIS" isn't. This Wiki is strict and you need it to be completely spelt out by the text that in this situation timeship = TARDIS, even if you and I both know that it is.
These rules are here for a reason. It stops two people coming along and writing two completely different facts about the same thing. :/