She's not just about to become a martyr, she knows it and is T-posing at them. In a sense, she has already become a martyr, and has started her post-Niji career despite technically still being in Niji.
She has receipts, she has publicly described in limited detail the contents of some of those receipts; and there's nothing Niji can do to her without admitting that not only are all of her allegations against them true, but things are actually significantly worse than she implied. And regardless of how they handle Aster, Scarle, Reimu, or anyone else even tangentially involved in this mess; tautologically, the only alternative they have to terminating Twisty is to NOT terminate her ( however see picrel ) and that would mean not publicly punishing someone who made them lose face.

With any luck, her Google Dockey is ready to go live as soon as they drop her white paper, and she'll tweet the link before anyone can finish reading the second page of her termination notice.