Pretty sure that person only assumed that because it was stated by staff members that there was only 1 dev for Cata and I think it was Wrath until they all started working on Lord.
So it would be safe to say that they must release all content on lordaeron (progression wise) and do "double tests" on that for them to apply the same core to the LK realms as a whole?

And btw, this isnt free.