I don't think Emet and gang had a good plan of action. I can understand where they were coming from for their end goal. but the course to get there was terrible.
Rejoining the shards on the other hand is something I could see helping them with, but not at the expense of everyone else. I expect that to be a plot point going forward since I would assume without Hydaelyn around the sundering should fade in time unless magic just lasts forever even without the source maintaining it.