The Empire definitely does not have the same goal as the scions. We want to end primal threats. That's it. The Empire wasn't to conquer. The Primals and stopping them is just a step in their overall goal. It's like saying "We want people to not be homeless. Slave owners want that too, cause homeless slaves aren't working for them. We have the same goals!"

The Empire has proven to be genocidal and absolutely ruthless. Just as the above gif shows. You say "war is like that" and yet, when Ala Mhigo warred with Gridania, did they massacre all the Ala Mhigans? No? So what the hell are you talking about?

There are to humans in Eorzea. Please do not relate our history to one of fantasy. And if you need to further proof of how horrible the Empire is, just look to Doma. Oh wait....sorry, look to the ashes that used to be Doma. Oh, you forgot? There is no Doma anymore, just ashes. Literally ashes. There is no going back to free Doma because there is no Doma left. Other Auri city states maybe, but not Doma.

So tell me again how Allying with the Empire is a good idea outside of trolling or going max edge villain mode?