I'm not THAT optimistic...yet, but that does paint the idea in a suspicious light.
Cap pointed out that it might have been that the field was simply left blank by
Dengeki, where the list came from, and in that case, they filled all empty fields in with TBA, like dates, players, etc.
The real question is this: did the ORIGINAL list from Nintendo of Japan have "TBA" listed under players for SSBB or did Dengeki add it in? If Dengeki added it, then the theory ends here.
But if it came from Nintendo that way, then I think this moves from "conspiracy theory" to "possibility".