That is more on editors...
Along with we have no idea when said issue was written. We within the last 6 months or even earlier and is just now coming out.
Point number 2 by Digified-there is no excuse for that because that book was recently active.
The rest fits with what you said. What is cannon and what is NOT cannon.
If PAD's YJ is cannon than that falls on the editor more than the writer. The moment villain was bought up-a look over of that run should have happened.