Safe Haven works by transmitting a signal in a localised environment such as a school, swimming pool, office facility or factory, which "disables the camera functionality of devices in the nearby environment", the companies claim.
If there will be a dedicated receiver circuit in the phone, operating on other than cellular frequencies, it will be fairly trivial to shield or jam or damage it. (Some countries, I think something Far-Eastern, want legislation to force the manufacturers to make the handset emit loud tone when taking the picture. A tiny switch enabling/disabling the transducer takes care of it rather easily. A non-tech approach could be to make the same tone popular as a ringtone, psychologically immunizing people against paying special attention to it.) If it will be a firmware update, it is matter of couple days or at most weeks until rogue firmware versions with blocking disabled pop up all around - especially if one of the blocked functions will be SMS messages in schools.