[collinf]

In the article they said that both regions consumed writes and got into an inconsistent state during the process.

> This effort was challenging because by this point the West Coast database cluster had ingested writes from our application tier for nearly 40 minutes. Additionally, there were the several seconds of writes that existed in the East Coast cluster that had not been replicated to the West Coast and prevented replication of new writes back to the East Coast.

[itsdrewmiller]

As I read it their solution to the east coast write conflict was to just put those aside and reconcile them later (and they are still working on that) - I don't think that would impact their ability to turn off east coast app servers too.