I did question this a couple of days ago in the Beta Spoilers thread If I had missed whether we had done anything about it or it had just been forgotten and the response I got was that the Maw is still sealed so the Jailer and his forces can't do anything about it. Despite the fact the Maw is explicitly stated to be sealed off from the Shadowlands, the tear literally being a physical manifestation within the Maw and the Mawsworn Kyrian having been shown to be able to invade Azeroth. I also questioned the logic behind the Helm being the thing that provided a "path" through the tear (considering it's a Maw Artifact after all and it's shattering also meant a big doorway could be opened and it can just do all these things (that the writers want it to) now) but all I got is Don't know how it works.
Basically the Writer's have created a literal plot hole that they're going to ignore until they feel it's relevant again. I feel it's Sword 2.0.