This is exactly the sort of thing that makes me think it’s really not so far fetched that Queenie would join Grindelwald. He knows how to make his cause sounds incredibly appealing. Queenie’s been told her whole life not to use her ability or if she can’t manage that then to hide it, but Grindelwald tells her it’s beautiful. That in his world she’d be celebrated for it.
I can definitely see her interrogating and manipulating people – she already supplied Grindelwald info about Credence’s thoughts, after all – and I think as time goes on she’d be more and more comfortable with it. I don’t picture her torturing people directly, but I do love the image of her standing there watching while someone else gets their hands dirty, constantly telling Gellert or one of his followers whether the victim is lying, what they’re most afraid of, how close they are to breaking, and maybe even feeling powerful for using her gift to help make the world better. Remember – it’s all for the greater good.