There are so many reasons for silent acquiescence in ISKCON.

First, there is the material dependancy. If you don't have anywhere to go, no means of support you will be afraid of ending up on the street.

Second, there is philosophical manipulation. 'One should not criticize senior godbrothers' 'Vaisnava apharada' etc...

Although there are other reasons, those two were good enough to cover years of corruption before the top blew off.