The Barclays terms for SUB eligibility are very vague:
From time to time, we may offer bonuses of AAdvantageŽ miles or other incentives to new American Airlines AAdvantageŽ AviatorŽ Business Mastercard cardmembers in connection with an application for a new card account. These bonuses and/or incentives are intended for applicants who are not and have not previously been American Airlines AAdvantageŽ AviatorŽ Business Mastercard cardmembers. You understand and agree that you may no longer be eligible for any bonuses and/or incentives in connection with a new American Airlines AAdvantageŽ AviatorŽ Business Mastercard account after this Card Account is opened. If you receive a bonus or incentive for which you are not eligible due to your status as a current or former American Airlines AAdvantageŽ AviatorŽ Business Mastercard cardmember, we may revoke the bonus or incentive, or reduce your AAdvantageŽ miles by the amount of the bonus or incentive, or charge your Card Account for the fair value of the bonus or incentive, in our sole discretion.
What are people's experiences with how/if they enforce this?