OK, speaking as a supervisor in a CAF Warehouse Technical Services organization, I can clearly state that when expired IMPs are returned to our facility, they are broken down, and disposed of. We have to strip the matches out and separate the cardboard into the proper waste stream.
There are some who, when doing this task, 'rescue' bits - I don't complain when someone saves a pack of the beef jerky, or a chocolate bar. That said, you're eating food that's already 5 years old...do you really want to?
Garbage.
My suggestion is that if you're looking for long term supply, go to one of the 'mountain house' type cans.
For short term emergency use? One of the MRE packs will do fine, but watch the life-cycle. Others have mentioned Costco being a good source for this.
Highly suggest a life-straw too.
NS