Those numbers don't add up. If only 20 staterooms were involved for 100 people turned away, then that would be 5 people per stateroom. Everyone's been saying that the maiden voyage had very, very few children, which implies that most staterooms didn't have anywhere near five people in them.When I read the post about positive testing for B2B after maiden voyage, the way I read it was that approximately 100 people were denied boarding. Not 100 positive tests. Negative people sharing a room with positive people would have been denied boarding also. I believe that post indicated that 20 staterooms were involved.
And, since they're using antigen tests for B2B cruises, there's a high chance that anyone sharing a stateroom with someone who tested positive will also have Covid-19, or will develop it over the next couple of days, even if their antigen test came back negative.