Club Penguin Exclusive: Dojo in the PLAZA?

Hey guys! So some interesting news, former Club Penguin moderator Rocketsnail, also known as Rsnail or his real name Lance Priebe was doing a Q & A about ninjas on his Twitter earlier, and questions were flooding in. He tweeted, about an hour ago, "Working on my blog post about the history of ninja penguins. Here is the original concept for the Dojo.", followed by this image.

Isn't that crazy? Obviously we know the Dojo actually resides atop the many mountains in Club Penguin, and was made a usable room in 2008 during the 'Dig out the Dojo' project. Before that, many penguins used to have snowballs fights and such in it. There was really no use for it. 

The image shown above is very very old, even before puffles were created, as you can tell from the Pet Shop. There is a dog instead of a puffle for the sign and the various posters across the window are to do with real-life pets. So I wonder, if the Dojo was moved to the Plaza instead, would Card-Jitsu ever of happened, what would the Dojo been used for?