no-one will take her seriously unless she publishes an actual detailed rebuttal of the black hole algorithm, rather than just sniping with her opinion from a blog.
It's nothing to do with what she feels like doing, or gatekeepeers, etc.
If she disputes the methods, she should make a substantiated argument - of course any format would be fine.
Maybe she doesn't want to work as an extremely underpaid laborer. Maybe she doesn't want to take emotional abuse from incompetent Pi's. Maybe she just got tired of it. Maybe it just doesn't spark a joy anymore. Just because she stopped doing science professionally doesn't invalidate her voice; after all this work is mostly taxpayer funded so in the end it all ought to be accountable to everyone, PhD or no.