What is this current notion going on that somehow moddability and bug fixing is somehow completely exclusive to one another?
By that logic - Counter Strike would have never been developed, Warcraft -> Starcraft would never have had any mods, would never have developed DoTA, even World of Warcraft wouldn't have had a single interface mod, and I am leaving out countless examples ranging from the old Red Alert 1 to things like Fallout 3.
Notice how every game designed for moddability was also patched in a timely fashion? In fact these games are usually patched the most because the developers actually care.
In any case, moddability usually has to be planned right from the start, and probably cannot be easily added on a completed project, and I am quite sure we won't be getting the source code of this game.