Very nicely worded UWD. You are right in feeling that you and your wife felt safe that you hadn’t tested positive at a moment in time, and granted, you were on a very long WC.
Our experience in May was quite different. No, we didn’t test positive. But we twice experienced our tests being labelled with other passengers’ names. We told guest relations about it and we were still allowed to continue with our day’s activities. We could have been infected and still socializing with others. We heard of several other people this had happened to.
We also talked to two couples whose spouses thought they might have come into contact (coughing, etc) with Covid, so the other spouse did spittings into both tubes to avoid the possibility of quarantine.
In an environment such as a cruise ship, these tests are only safe if they are proctored.