Hey Nicholas. Those semantics are kind of surprising to me. As I remember the motivation for the feature, the idea is to reduce the likelihood that a long-running pipeline completely fails. Given that, it seems preferable to continue with 2 or 1 replicas in the pipeline if there are no more nodes left in the cluster, rather than fail if it can't recruit a new one.
That is to say, if you had a 4-node cluster with the feature enabled, it's actually going to have pipeline failures more often with the feature enabled than with the feature disabled, statistically speaking.
That said, that's a separate question than this patch. So, if you believe the feature is working as designed, then +1.