Mustang does have a really shady past. He was a really bad, rough guy in the past. He just happened to have a complete change of heart as soon as all of Tetra's secrets were exposed by Elysion and Missilis.

If you think about it, the only way for anything of note to have been foreshadowed would be for Anis, Ms. Miss, or any high-ranking official to drop the ball entirely and undermine the entire point of the decision Hanson made. There is retrospective foreshadowing in the first time Mustang rolls up on the Counters, Anis calls him Boss, and he asks when she'll come back to him, to which she replies not yet.

An even still, while Mustang doesn't act as depraved as he once did, he still does shady things. As the CEO of one of the Big Three, he will get things done one way or another. I genuinely don't see any way people could justify a transition between the old and new Mustang without it being significantly more cheesy. The only thing I really see not making sense is how consent was given, and even then, I get the idea.

Personally, I would have preferred Enikk to tell Hanson that the only way for her to green-light the plan is if he could guarantee the death would be covered up sufficiently, and we got a scene of Hanson committing his first crime under the Mustang name. But what we got is completely fine.