Since Giffin is known for being more of the plotter when it comes to his co-writing duties I do assume that Winick has more to do with this Max. Yes, he was part of the group that wrote Max in CTIC along with Johns and Rucka. But Winick does write excellent anti-hero/anti-villain characters such as Jason Todd. He's one of the few writers at DC that can truly understand that there's more than white and black, there are shades of grey. If Giffin/DeMatteis created the character and reminded us of his depth in BG then Winick made him a truly intriguing character while still being the bad guy. None of the other writers during or after CTIC really bothered making the connection from the old Max to this one. Johns went as far as stating Max was always the bad guy.
Winick doesn't say that at all, he shows at the start of Justice League Generation Losts' first issue that there's more to Max than that. Superman goes out of his way to make this clear when he gives a statement at the start of their search. Max wasn't always like this, he did have good intentions. His scene with Booster remains my favorite part of the whole series because it's obvious that despite being on different sides (despite what Max claims) their friendship matters. For the first time Max tries to explain himself and it works where other interpretations failed. This isn't the same guy depicted in Sacrifice that told Wonder Woman he was guilty as charged for Teds' murder with a slight smile. He shows remorse over having to kill a friend admitting that he's still haunted by it.
Although he still has his cocky chessmaster like moments Max shows real emotions. His moments like his desire to bring his team back together feels right. There's a real honest feel to his interactions. His emotional scenes with Booster show him at his most vulnerable.
We're reminded that the JLI wasn't a group that Max threw together in some grand quest for power. He truly wanted to help better the world. Mentions of him intentionally making them appear in a negative light (as outright stated in CTIC and Johns run on BG) aren't brought up. (Although he does make them look bad for his plans to work in this series that retcon isn't mentioned.) Max knows these people are good, he holds them as the heroes that rank a higher standard than the rest. Even if he thinks their too soft hearted to do what's needed.
The crux of the story seems to be about the team (especially Booster) facing a former friend. Max confesses that he still thinks of them as his friends and doesn't wish to harm any of them, even apologizing to Booster at more than one point. The importance of Max recruiting Booster isn't forgotten and we see that it's a moment that means a lot to both men. A huge improvement over Max deriding Booster at every turn and far more interesting. Instead of coming off as an one dimensional bad guy that only thinks of himself Max comes off as a misguided man who is frustrated with no one else understanding his reasoning or seeing the bigger picture.
The reason for his turn is finally given and while it's not as fleshed out as much as it could be it makes sense. It's tragic on a level Max himself doesn't realize as he essentionally becomes the sort of man that murdered his father. What he does with the memory of Ted Kord only underlines this. His journey is reflected in what he thinks humanity entails in comparison to the teams' own struggles. If Max has to be the bad guy then this is the best of show.