A trip interruption typically means having to interrupt your trip and return home due to some emergency: death or life-threatening injury or illness in the immediate family, your house being damaged or destroyed by fire or natural disaster, and the like for example. It does not normally apply to the tour or cruise company changing the itinerary due to weather, port or hotel non-availability, etc (which almost all travel companies include as a non-refundable event in their contracts with you). It could also apply if the ship was damaged and had to return early to port (or worse, sunk).
You can certainly ask for a refund from your
travel insurance company for not making a specific port call, but it's unlikely they will allow it as being reimbursable.