The guy wasn't stick stirring and it's a legitimate RL maneuver called a negative G pushaway typically used as a guns defense. As the NME fighter is getting ready to gun you in a turn you simply stuff your stick forward. It works for two reasons. The first is that everyone expects you to pull harder as he saddles up for a tracking shot so you have the element of surprise. The other reason is that all aircraft have to pull lead for a tracking shot and a pushaway can easily cause him to lose sight. The trick is to time the push just as the NME pilot is about to pull the trigger. Done correctly it's a very effective technique and can easily result in scissors or role reversal.
So, that's the positive side, the negative G pushaway is perfectly legit. Now, the negative side (no pun intended). Most pilots can't do it effectively and certainly not in the repetitive way you see in the film and there are several problems beyond the redout that many have mentioned.
First, it's extremely uncomfortable (always) and unnatural (unless you're an experienced aerobatic pilot). Do this more than a couple times in a row and you're a hurting puppy. Also, ask most pilots to push negative G and then check the G meter. You'll usually find that most pilots think they went negative when in fact they only pushed to zero G which doesn't really work that well as a guns defense. BTW, this is one of the first exercises they had you do at TOPGUN because nobody ever really pushes to negative G, they have to be trained to do it.
Second, from an even more practical point of view, cockpit restraint systems (harness and belt) typically do a lousy job of keeping you in your seat during negative G's unless you have them as tight as possible. Unfortunately, having the belts tight enough to keep you firmly in the seat during negative G also restricts your ability to turn around in the cockpit during ACM so most guys fly with them "tight" but not really ball-buster tight. It's basically a choice between keeping sight and being fully prepared for negative G. Everyone I know will chose keeping sight. Even ball-buster tight doesn't work that well because the typical belt pulls you back and down so you still pivot up and back (i.e., away from your controls) during negative G. Basically, as you get to 0G you're "floating" in your seat but as you get to negative G you're hanging upside down from it and usually your head is against the canopy. This is true for me even though I'm only 5'6". So you might ask "so what?" Well, if you're hanging from your harness your feet are probably off your rudder pedals and you can't keep the stick forward enough to sustain a negative G turn. You can do a hard push to negative G (if you've practiced it) but it's only for a second or two unless your butt is nailed to the seat or your harness is as big and strong as Chuck Norris' jock strap.
So, is the maneuver legit? Yes. Could he do continuous negative G maneuvers back-to-back as in the video? While theoretically possible I'd say no way.
