They absolutely do get that opportunity. In some cases, the decision is then overturned. However, in this case, it was not a single report that caused the banning. It was several reports from different users. SR Admin always investigate and unless they have actual proof, then they aren't going to ban the vendor - they'll just keep an eye on the situation. In cases where it is obvious and blatant and proof has been provided / found, then they ban them outright. Still, he had the opportunity to plead his case and provide proof to support his claims. If he provided any proof of his own, which I don't think he has.