Ironglow,
As a "tuned" "well-maintained" "with Armorer support" platform, the AR is sufficient for our nation's military needs. The reason I bought an AR was because it is a very accurate weapon when tuned and I tuned mine, and I feel sufficiently confident in my own abilities to support it that it met my shooting objectives for the time I had it. I don't hate the AR platform at all, and have been issued one for over 20 years now. Your son's experience rings true; many thanks for his service by the way, what unit was he with - if he was there 2006-2008 we may have crossed paths.
The topic here though is survival, specifically a single person and one rifle and no support - I may have mentally added EOTWAWKI in my replies. Not military operations, not in a unit supported environment, not a well trained professional fighting force with dedicated time for cleaning, since things like food, water, shelter, medical care, etc. are all provided. In this scenario, the ARs and AKs will not fare well in the hands of most of the folks who own them because they will not be cleaned well or often - armorer support and parts probably won't be readily available. And they'll be doing most of the important work during the 12 hours of daylight to preserve what precious fuel/energy they have, things like solving the questions of food, water, medical care, sewing, cleaning, maybe sleeping since you travel mostly at night perhaps if you travel at all. All of those other things will take a disproportionately longer amount of time than at home - especially figuring out how to keep food from spoiling. There's no safe perimeter so you need to be in condition 1 most all the time, so a thorough take down and cleaning will seldom if ever happen. The list is huge, and most days you can count on being too tired, hungry, or sick to do everything well.
Survival to me is a mindset predicated on taking nothing for granted: expect nothing, leverage everything. And if you're a husband/father, the first assumption you should make in your survival plan is that YOU are dead. So if any of the survival gear requires my presence to be effective, then its no longer the right piece of gear. Your son may have learned how to be an armorer from his Mom in which case keep an AR (and I'm jealous). The next oldest man in my house is 13, and he's the youngest, so the AR had to go. If I am gone, he needs a primary long gun that is an extension of him and he can grab on his way out the door with no expectation of ever getting new parts, or proper maintenance support. Same for my wife and daughter.
S/F,
Chaps