That is a great idea! Do you reach out to companies after adding them to the public list of shame letting them know, or do they eventually discover then are on it? I may have to implement this..
I had someone well known in the local tech community call it "The most unprofessional thing I have ever seen" but later he was using it as a sales tool to persuade one of the companies listed to hire him to upgrade their site. I don't condone this but once the info is public I can't control what people do with it.