You know, you guys are focusing on the technology being stuck in the past, but here is another scenario, that did play out in the movie with a better what if....
Remember that the ship wasnt left behind but CAG was. He would be the next best thing. We dont know if he went on to military service or not. Realistically, he could have as his age, while older, wasnt a factor. But how could he explain his military history to a group of people that has never heard of 70% of what he knows? He could play it off that he learned to fly his dads crop duster, and make a few things up along the way. But now he is flying an aircraft that has a less than 1 to 1 thrust/weight ratio. Basic ACM concepts are similar but he has no platform in which to demonstrate his ability that has the performance. And his flying skill in even the hottest aircraft of the time, is less than the guys he would be performing for, because they would have had more seat time in that aircraft.
So chances are he becomes a government contractor and dabbles in areas where his expertise can be "explored and discovered" without raising too much suspicion. But now, he has taken 40 years of technology and gone back in time, to give it a 40 year headstart. The come away from that is, that had he NOT gone back in time, how much less technology would the military have by 1980? Did he exploit his knowledge, or did he keep it to himself and feed it out as the time in history came about, so the sidewinder missle would be developed in the 50s instead of the 40s?
The other thing is that while he was a knowledgeable, experienced and educated man, he probably wasnt a subject matter expert in any one field. He knew the major components of a jet engine, but he couldnt tell you specifically and exactly how each part fit, where it went and so forth. He knew a missle has a seeker, warhead, guidance and propulsion, but does he knew exactly how the seeker sends information to the guidance system? So while he has the advantage of "knowing" about 40 years of technology, how much of that can he actually implement with first hand knowledge? Its not like he went back with blueprints in hand.
I think he had enough knowledge to guide technology until the technology could actually be developed. Remember, things like circuit boards were still 15-20 years away, a main component in missle and "smart" technology. As noted in the film, he had implemented many of the designs that went into the construction of the ship (presumably Nimitz class carriers) so maybe that is what he focused on?