Here are the terms for the existing American Express personal Bonvoy card. The terms specifically mention closing within the first 12 months as an example of
abuse, misuse or gaming. The terms do not mention retracting points already awarded, but they do mention closing other card accounts -and- we know that this type of behavior can block the ability to earn bonuses on other American Express products.
If we in our sole discretion determine that you have engaged in abuse, misuse, or gaming in connection with the welcome offer in any way or that you intend to do so (for example, if you applied for one or more cards to obtain a welcome offer(s) that we did not intend for you; if you cancel or downgrade your account within 12 months after acquiring it; or if you cancel or return purchases you made to meet the Threshold Amount), we may not credit points to your account. We may also cancel this Card account and other Card accounts you may have with us.