MREs are NOT prohibited items. The flameless heat element IS prohibited, but this would not result in the entire packet being prohibited. In checked baggage, they are permitted as long as the MRE packet is still intact. Otherwise, if opened, the packet is prohibited.

The point of this thread is that food was apparently taken away from people in great need of it. I tend to doubt that happened solely because the MREs alarmed a metal detector. There's more to this story than what we're being told.