That's fine if your insurer guarantees your cover. It would appear however the cancellation is based on proof you have covid whereas P&O policy is not apparently medically confirmed and is just computer driven.
The case I mentioned previously which made me look at it was a lady who declared she had a cough. She did not have nor ever had covid but was on antibiotics from her doctor for a chest infection. She was refused boarding. Her sister and family had to travel without her as they hadn't answered the questionnaire with yes anywhere. The lady appealed and was told by P&O no appeal or discussion allowed as it was for the ship safety. She is now fighting her insurer who says no cover because she hasn't got a positive covid test. It continues but is understandably very distressing and difficult.
We have three policies here, Allianz through our bank, Post Office for me as all singing and dancing nothing not covered and Avanti for my husband because of winter sports cover with health conditions. All three say you require proof of a positive covid test to claim under their covid section, including denied boarding. It also has to be confirmed by a PCR, the observed LFT requested by P&O for my Caribbean fly cruise does not suffice.