They aren't much of a survival rifle. A survival rifle must be accurate and dependable; the AR-7 is generally neither.
A Marlin Papoose or one of their take-down lever guns would be better choices. So would an NEF .22, since they can be taken apart quite easily; and it would be inexpensive, too. You could stick a good folding stock on a Ruger 10/22, if Marlins and NEF don't appeal to you. There are still yet more options if you can use a handgun well.
"But wait!" you cry, "the AR-7 floats and those others don't!" If floating is important, just use a floating gun case. The Papoose comes with one. A similar one can be purchased or made pretty inexpensively for the other guns.
Once you commence to surviving, gimmicks like floating and coming apart don't matter. You're going to put the gun together and leave it that way. You're going to want it to absolutely and for sure go bang and put the bullet where you were aiming. Malfs and misses when you are surviving are seriously bad juju. They both mean going hungry, for sure. Misses mean wasted ammo at a time when every round is critical.
AR-7's are an okay idea that has but seldom been executed well. They're a gimmick gun and a range toy. Would I choose one as a survival rifle i.e. bet my life on one? Not hardly.