Perhaps a reference to the actual Terms & Conditions of the Amex Companion Voucher might be useful at this point.

From the Terms & Conditions:

1. You can only receive a Companion Voucher if you are a Member of the British Airways Executive Club and are the main Account holder within a British Airways American Express Card Account (a “Cardmember”).
…
Cardmembers must remain eligible for use of the Companion Voucher in accordance with these Terms and Conditions and the British Airways Executive Club Terms and Conditions at the time of travel. British Airways and American Express reserve the right to refuse to issue or honour any Companion Voucher or cancel Reward Flights booked using a Companion Voucher in the event that the Cardmember is in breach of the terms of the British Airways American Express Card or the British Airways Executive Club Membership (including, without limitation, events of Fraud and/or Misconduct).

https://www.britishairways.com/en-gb...amex-companion