Amazing how one email can generate so many theories on it's intent. Clearly, if you read the email, it states that those cashing out after playing BJ is the issue. If a sudden change in policy regarding audits and cashouts has been instituted, especially for those who played BJ, doesn't that indicate that there must have been a major problem with bonus abuse/BJ/Cashouts.
Additionally, if players are having their bonuses confiscated and/or accounts locked, surely that tells you something. The email gave the player the "option" to retain the bonuses given or cashout quickly. I can only imagine how many accounts need to be audited after the opening of a new casino.
It seems unfair to jump to conclusions of financial instability; pushing members to forfeit winnings; recouping money; about a group of casinos that have only had a solid history of paying winners, offering numerous bonuses, and great customer support. Changes made (at any casino) are often the result of problems with players.