iMessage is diabled when camera is disabled
If you disable the camera using the iPhone Configuration Utility, it disables iMessage. There is no logical reason for this to be the case. I understand the true link is between Facetime and iMessage, but when the camera is disabled, so is Facetime.
Also, disabling the camera disables use of the LED flash. There is no reason to disable that. Separate the options!
iPhone 4, iOS 5, 4S, iPhone Configuration Utility