"I'm the PC, it'll be different, she really actually likes me".
Oh-ho-ho, yes, this could certainly be part of that. But I think you are actually selling this short. The genius of the finale is that when you have this back and forth with the cabbie about the story so far and about how you might get out of the mess of being hunted by pretty much every single kindred faction out there (presumably you killed a beloved Anarch leader, betrayed a Camarilla prince, foiled the Sabbat and spited the Giovanni), the developers take control of the discussion in a very subtle way. The player is allowed to express character through a number of very diverse views on LaCroix, the fate of the Anarchs and such. Through that scene comes the rationalization behind every single choice. And the Kuei-Jin option comes after you rule everyone else out:
"The Anarchs are done for without Nines."
"LaCroix tried to kill me."
"There's nobody left to take over the Camarilla." (in case you choose not to follow up with the Strauss ending).
"I'm going to die out there without support."
And so it boils down to "I don't necessarily like the Kuei-Jin but they are my only choice". The cabbie even warns you against it.
Now, that much is evident. What is really interesting is how that came about: a proposition from Ming right after killing Andrei and showing off your power. This, mind you, after Ming's been scheming against you from the shadows since the moment you stepped foot in Chinatown. And all of a sudden she's willing to put all her cards in the table? Does she fear you that much or is there something else going on here?
Fastforward a bit to the werewolf park. The fact is that he called a Blood Hunt on you. So it does make sense that LaCroix tried to kill you. A player with an engorged ego might rush to this conclusion after Ming's proposal and Andrei's little tirade. But its not like LaCroix isn't used to having henchmen who are more powerful than him. That's what the Sheriff is. In fact, he was never really sure of himself. He was always a coward, wether you could kill ancient Tzimisce or not. So perhaps the issue is that he grew uncertain of his own ability to control you. That does explain why in the end you can still choose to go back to Ventrue Tower in an amazing show of loyalty. But there's still one question that lies unanswered:
Why would he wait so long to kill Nines?
Take a moment to step back and look at the Los Angeles chessboard. There are four factions vying for control: the Sabbat, the Camarilla, the Anarchs and the Kuei-Jin. Presumably, diplomacy isn't really possible for the Sabbat and they are at war with everyone by default but especially the Camarilla. Meanwhile the other three are held frozen by a tenuous balance of power.
For the Anarchs L.A. is home turf so they have some sort of advantage there. However, they are also barely held together by charismatic leadership and for that they suffered a critical defeat at the hands of the Kuei-Jin recently. Ironically, the only thing that kept the Anarchs from final death was that the Camarilla stepped in and made things more complex.
The Camarilla are possibly the most widespread faction. However, they are fractured in clans and primogens, their Prince is weak and they are all the primary targets for the Sabbat.
The Sabbat's only real interest is undermining the Camarilla and securing the sarcophagus.
Now, the Kuei-Jin are truly alien to it all. They are a minority, but they are highly organized and unified. In turn, the only thing keeping them from defeat is that the Kindred haven't yet decided they hate Kuei-Jin more than one another.
So who benefits from a rightful death of Nines' Rodrigues? LaCroix, certainly. That's where his plot with Ming comes in. The last and greatest of the local Anarch leadership is gone, the faction is broken and the Camarilla moves in to unite the Kindred. Against the Kuei-Jin. Now, who'd benefit from Nines' prolongued survival and increased tensions between kindred as the Blood Hunt lasts longer and longer? In other words, who'd have the time to actually set up the ambush against Nines from the moment you, LaCroix's eyes and hands in this town, actually finds out where he is? Ming Xiao.
As with the Mandarin so was the Werewolf another ploy to get you killed. But this time Ming's gambit accounted for your likely survival. All of a sudden her friendly approach sounds much more interesting than it actually is. You forgot that Jack is just another character, that he's fallible and that more likely to just blame LaCroix for the werewolf attack with no real evidence. You forgot that the Kuei-Jin hate all of the kindred. As far as you know Nines is really dead and LaCroix tried to kill you. And you fell for it.
You fool.