If he is not involved, what do these scenes imply?
These scenes imply that Votto is involved in one way or another for sure. Also I would like to point out that the scenes were shown through Joe's eyes, as if we are are observing his thought process. so any conclusion we come to will be from his perspective. The movie does not point out saying this is this and this is that.
It seems that Senator Votto might not be Nina's father at all.
At one point in the script, it is said that:
He stands and grasps a clear plastic file and places it in
front of Joe.
VOTTO (CONT’D):
I got a text message this
morning. Anonymous.
Joe reads the text as Votto paces.
VOTTO (CONT’D):
(by heart)
‘Your daughter is at 544 West
38th street I couldn’t live
with myself if I didn’t let you
know’....
Also,
...Another photograph - formally posed, the girl wears a white
party dress as Votto holds her in an embrace, their eyes both
closed, his chin resting on the crown of her head.
Joe selects the earlier selfie of the girl AND A FAMILY
PORTRAIT - NINA between Her Mother and Father...
A lot these were not shown in the movie, though we can see a photograph of a man embracing a girl on the table. From this we can assume that the senator was not lying about the girl being his daughter, the movie tells us nothing more than that.
Nina also doesn't seem to have an emotional reaction after seeing the news report on the TV about Senator Votto's death.
As you have said, Votto is inivolved and going back to him would make Nina his victim again,that's why Nina is so indifferent to her father's death.
If Votto is involved with the pedophile ring, why would he have Nina rescued?
Votto might be directly involved with the ring or might have taken the advantage of his knowledge of the governor's secret trade. He might have forced his daughter to go to the governor to rise in political power, which might be the reason behind Nina's running away from home. Earlier she was found by the local police, but this time they probably couldn't find her and Votto might have freaked out about his career. Nina can defame her or he can defame the governor if he can find Nina. All these are speculations. At the end of the day, without her Votto has no upper hand to the governor. This is why he was so eager to find Nina.