Considering that Nutaku didn't even have a friggin' DATE for the time it's closing and that the Nutaku facebook people seemed rather surprised themselves, odds are rather high that it wasn't entirely Nutaku's decision to make.

As for all those other signs and hints that Nutaku might have been planning to close down the game, many of those could also instead have been signs that Nutaku was trying hard to negotiate the right to continue and didn't say the game was closing down back then simply because it was still up in the air and they thought they could still retain the right to keep it going.

Alas, the full extent of what happened will probably never be publically known.