Qantas often blocked empty seats for me for international flights but sometimes won't. Who decides ?

Even if you have a Ticket and a confirmed reservation, we may refuse to carry you and your Baggage if any of the following circumstances have occurred or we reasonably believe will occur:

• if carrying you or your Baggage may put the safety of the aircraft or the safety or health of any person in the aircraft in danger or at risk
• if you have used threatening, abusive or insulting words towards our ground staff or a member of the crew of the aircraft or otherwise behaved in a threatening manner
• if carrying you or your Baggage may materially affect the comfort of any person in the aircraft
• if carrying you will break government laws, regulations, orders or an immigration direction from a country to which you are travelling or are to depart from
• because you have refused to allow a security check to be carried out on you or your Baggage
• because you do not appear to have all necessary documents
• if you fail to comply with any applicable law, rule, regulation or order or these Conditions of Carriage
• if you fail to complete the check-in process by the Check-In Deadline or fail to arrive at the boarding gate on time
• because you have not obeyed the instructions of our ground staff or a member of the crew of the aircraft relating to safety or security
• because you have not complied with our medical requirements
• because you require special assistance and you have not made prior arrangements with us for this
• if you are drunk or under the influence of alcohol or drugs
• if you are, or we reasonably believe you are, in unlawful possession of drugs
• if your mental or physical state is a danger or risk to you, the aircraft or any person in it
• if you have committed a criminal offence during the check-in or boarding processes or on board the aircraft
• if you have deliberately interfered with a member of our ground staff or the crew of the aircraft carrying out their duties
• if you have put the safety of either the aircraft or any person in it in danger
• if you have made a threat
• because you have committed misconduct on a previous flight and we have reason to believe that such conduct may be repeated
• because you cannot prove you are the person specified on the Ticket on which you wish to travel
• because you are trying to use a Flight Coupon out of sequence without our agreement
• if you destroy your travel documents during the flight
• if you have refused to allow us to photocopy your travel documents
• if you have refused to give your travel documents to a member of Our ground staff or the crew of the aircraft when we have asked you to do so
• if we reasonably believe you will ask the relevant government authorities for permission to enter a country through which you are Ticketed as a transit Passenger
• because your Ticket:
  • is not paid for
  • has been reported lost or stolen
  • has been transferred
  • has been acquired unlawfully
  • has been acquired from someone other than us or an Authorised Agent
  • contains an alteration which has not been made by us or an Authorised Agent
  • is spoiled, torn or damaged or has otherwise been tampered with, or
  • is counterfeit or otherwise invalid.

In any of the situations in this 10.1, we may remove you from a flight, even after you have boarded, without any liability on our part, and cancel any subsequent flights on the Ticket.