On one hand, I can completely get behind letting people do what they want in a private thread. I can even get behind people making ridiculously overpowered Factory submissions and only using it in private threads for story purposes.
TLDR : Let people use whatever banned stuff they want, provided its tagged as Story only. It's not going to impact on those who haven't chosen to be part of said story.
The issue with using banned tech is that it creates story continuity problems, especially since stories can start out as private affairs that very quickly become public, even almost board-wide affairs. It's not a clearly demarcated line.
Let's say that we use that teleportation submission that you made. What happens if that same ship and location of the receiving station are in the same positions they were in the past during a story thread, but now it's become a competitive environment (skirmish, invasion). It's hard to not justify using stuff like that from an in-character perspective then. If you could teleport to a strategic location instantly, why wouldn't yourather than take the time to jump into a shuttle and take the time to travel there with the additional risk of getting shot down?
The other issue is that private story threads can later have an impact on public/interfaction events. As a good example of this, consider the ME dominion of Eshan and then the resulting invasion that occurred afterwards. What was clearly a private affair became a massive board event. In cases like these, it's quite possible that the people coming into these events won't have any say in the background of those stories.
Factory doesn't judge on balance..?
The Factory doesn't approve or deny subs based on balance alone, but we strongly recommend making balanced subs, especially if they're going to be used in competitive environments.
That does not mean that theFactory won't pre-emptively regulate subs based on other things though, suchas the concept of superweapons, banned technologies, or the 'what is Star Wars' principle.