Rereading the update more carefully, I think I have to grudgingly accept that there is merit in building some goodwill with Bai Jiutian.
The amount of time that it takes for him to reply tells you that this turn of events was certainly unexpected to him. Finally, he says, “Why are you telling me this? I… I cannot believe you.”
“You sent me Zhang Manxing as a present after all. Clearly you do not care for him or the wishes of the Zhang family. If it makes you feel better to believe that this is my way of making up for failing to kill him… well, go ahead!”
[...]
“I don’t have to be your enemy,” you say. “You are already making plans to separate yourself from Master Nie and the Zhang clan, aren’t you?”
After all, these were our own words. He is in doubt whether or not he can trust us enough to work with us. I guess if we want to prove that we meant what we said, we'd have to get involved.
And I think at least a part of his motivation is established:
“You have been a thorn in the side of Madam Nie for a long time now, Xu Jing… but I might not pluck out that thorn today, depending on what you say.”
We have noticed back at the Young Tigers Tournament that he might have acted at the behest of someone else, and there was that inexplicable attempt to attack us at the Black Tigers Valley. It all makes sense if he was carrying out the will of his
shimu who picked him up 'when no one else would'. If he wants to distance himself from her, it is a good sign, and we should help him find allies elsewhere.
“Well, no matter what you say, they certainly don’t like you. If they’re that dangerous…”
“…that is right,” he admits grudgingly. “But that only means I need to find ways to protect myself from them instead of relying solely on my shimu.
Speaking of which, the woman has quite a Lady Macbeth vibe about her. Guiding her husband's ambition, manipulating his best disciple and trying to play zhang clan while simultaneously committing treason (if she was involved with Youxia events) takes some serious balls and cunning. When did we manage to cross her? At this point it is safe to say that the incident in Songfeng was her doing, but what else did we do to warrant the status of her enemy and make her sick BJ on us? We never quite learned who planned to implicate Zhang Jue back at the tournament, even though we dodged all attempts against us or Guo Fu. That one might not be hers, though. And of course, our stint in Youxia didn't endear us to her at all. I'd say, she might prove to be a worse enemy than Wuxing and manlou combined.
Regardless, I am very hesitant of trying to kill manxing after being burned the first time. Even though I have to retract my point about manxing having hostages with him - he couldn't have afforded such a drastic move if all he had was a lingering suspicion, - still, he must have some kind of a safety network with him if he thought that BJ is out to kill him. Engaging him in battle blindly just does not sit well with me, considering our track record.
I guess C would still be more acceptable to me than B. But we might get in the way of BJ, and end up with some unforeseen result, not unlike what happened in Tufan. Let's just hope manxing does not have that aphrodisiac with him. If Jing and Juitian both get hit, things might get awkward.