The text of the article featured one of the developers alluding to the fact that it's easier for them to update and iterate on the PS4 than it is on X-Box One (I'm inferring and paraphrasing, so take this with a grain of salt), which is why it is planned (for 2015 at least) to be a PS4-only console game. The exact language the interviewee used was very vague. Hopefully, the article will go back up soon and maybe we'll get an official announcement.