It just seems like some tweaks need to be made. The DLC is probably mostly fine otherwise, so why not let those who bought it enjoy it?
- Moving it to Chronicles would be simple if they decide to do that.
- Changing heroes to something non-hero and figuring out a different uniqueness would be fairly simple.
- The Khitans and the Tanguts issues, camel-pults, etc. issues sound harder to fix probably, but maybe could be addressed with all hands on deck post-launch
One day or week of work, problems solved.
I can wait a week or so for launch if devs need more time. Tbh, though, the DLC says they “plan” to launch May 6th 
They could very well delay it for long time if needed: “This game plans to unlock in approximately 2 weeks”