I haven't been doing much of any ship to ship combat since Odyssey came out, but these claims long predate that, and in ~7k hours and some ~60k NPC kills of all sorts, I have never seen a (human) NPC ship clearly do something that is not possible for a CMDR to do, with flight assist enabled, unless it was a bug that was openly acknowledged by Frontier.
Oh, I believe you, there are oddities others have reported - with video evidence - that I've never seen in my thousands of hours - I've been around since the Beta. Indeed, lots of people have never seen the "Wanted" ship, changing to "Clean" the moment the Player shoots it once bug - myself (and others) got a lot of doubt on that...until the video(s) of it were shown. I'm sure there are numerous examples of issues some in the community experience but others, with thousands of hours, have never seen. This one is the same. It seems to rear its head from time to time. I had it clearly appearing last night - first time in a long while (pre Odyssey perhaps) to be honest - yet during my play session just now, everything was working perfectly. Same ship (Chieftan) same HAZ Res in LHS 317 Dangerous and Deadly Anacondas once again. Sure, there may well have been outfitting and Engineering differences, but the ships today did nothing I'd consider unusual and I had no issues staying on their tail. They'd still boost, turn and try to face me of course, but they'd quickly start moving along the vector they are facing, making it easy for me to slip back behind them. Much of the time they never even managed to face me doing this manoeuvre.
I can't explain what's going on here, but you've got to admit that seeing something like an Anaconda, travelling backwards at speeds of over 400 m/s for extended periods as the player closes on them (face to face) is going to raise some suspicion that things aren't perhaps working quite right at that moment. I'm glad you've never experienced it, it can be a little frustrating when it happens, but myself and a number of others have.
Like I said, I'm not overly concerned about it and I've not seen it much in quite a few hours of play - though I have just come back from a bit of a break. It was just a bit of an "Oh, that one again" moment last night, when my 500 m/s+ Boost was barely seeing me close in on a reversing Anaconda.
As an aside, reversing can totally confuse the AI. My current ship has fixed Long-Range Pulse Lasers - more for the damage falloff reduction than the outright range - and Rail Guns. I was fighting an enemy (Clipper) that started to get the best of me, thanks to his two wing-men. I boosted away, primarily to let my shields recover, then flipped over and started shooting him from over 5km away, while reversing - though not fast. At first he made a bee line towards me, closing the distance fast, but as I did more damage he eventually broke off, flying away for a bit before heading back. I was landing shots the entire time. At no point did he enter his weapon's range, so I killed him without being hit again. If he'd continued closing on me, I'd have had more of a challenge. One of his surviving allies (Viper IV) did eventually close in on me while I was concentrating on him, but that one-on-one fight was easier.