Stifling TFA's Critics?

I have heard an account that I find credible, that participants in Teach for America are not permitted to publicly criticize the program, at the potential peril of their being expelled from the program. Given TFA's apparent emphasis on its program as résumé fodder, this seems to be part of an interesting set of techniques that TFA uses to minimize criticism:

• If you're in the program, you're required to keep negative opinions to yourself;
• If you are kicked out or drop out, criticism is seen as "sour grapes";
• If you complete the program, you have an incentive to defend it as otherwise its value as résumé fodder is diminished;
• If you're an education professional who criticizes the program, it seems to me that you're depicted as a defender of a failed status quo, as shilling for unions, or both.

I'm personally wary of any program that bars participants from publicly commenting on the negative aspects of their experience. I would be interested to hear any verification or rebuttal in relation to that alleged policy.