I’m not a lawyer…
I think you should be ok for travel insurance.
The spend criteria for eligibility is as follows (my bolding):
International Return Trips
4. You are going on an International Return Trip and You pay the full
amount of Your outbound ticket for a Scheduled Flight or Scheduled
Cruise leaving Australia on Your:
i. American Express Card Account;
ii. corresponding American Express Membership Rewards points /
Qantas Points / Velocity Points (where applicable); and/or
iii. Travel Benefit.
So, if you are flying offshore to join your cruise, then the Outbound Flight should satisfy the eligibility requirements.
