I'm not saying this will happen, but a known figure disappearing in the city could be enough to rouse Celestia to become more involved because of how it is similar to the changeling disappearances. I'm not trying to fear monger cause that's potential worst case and I doubt it'll happen- ect...
Celestia won't. I say that will full, nigh absolute certainty. If I'm wrong, egg on my face but...
Celestia did nothing when one of her appointed few important ponies, Velvet herself, was attacked. If memory serves, her words were "You have a busy month ahead of you" or something to that effect. She seems to be done babying ponykind. She is focused like few things are, and that focus is not anywhere even close to the disgraced nobles she herself has all but dismissed.
I know you said you doubt that Celestia would... but I know what priming looks like in a discussion to try and give weight to other claims. And it looks like that.
Velvet Hill... gegh. I don't think the problems that are going to come from it (because there will be) will be overmuch in the physical side of things. It's going to be much more on Velvet Covers herself. It's going to be a mare who tries to do the right thing, who wants to be good and recognizes there are hard decisions that have to be made. And it's going to be her picking the easy option for something. It's her picking something close to vindication. It's cruel, and it's vicious and it's vile and it's harsh.
It's Velvet seeing the problems coming down the pipeline and seeing things she might need to do to be prepared. It's Velvet looking at her timeline and her funds and the world and saying she needs an answer. That someone has to die in a truly cruel and terrible way. This is Velvet Covers deciding her father should be the one to suffer that fate. That he will die by her hooves, and she should benefit from it. She will make excuses, understand and weigh the decision and will even lose sleep over it. But it's an understanding. For her to have the power to keep the people she loves safe, by the means she knows... someone is going to have to suffer for it.
So she is picking someone that made her suffer. That felt no remorse. That Lived and Hated and gave up on her. And as much as Velvet has moved past it... she could let it sit.
Or. She could use him as an excuse.
I am under no pretense this is Good. Maybe Fitting, or Narratively Interesting. But this is not Good. This is Bad. Cruel. Malicious. Violent and Hateful.
I do not envision Velvet as a paragon of good. Nor do I see her as some megalomaniacal Villian. She tries to be good.
This is just one place, that I feel she... she doesn't try to be better here.