The article you linked talks about the voice personality prompt for "unhinged mode", which is an entertainment mode. It has nothing to do with the code writing model.
The great thing about xAI is that it is just a company and there are other AI companies that have AIs that match your values, even though between Grok, ChatGPT, and Claude there are minimal actual differences.
An AI will be anything that the prompt says it is. Because a prompt exists doesn't condemn the company.
Within the boundaries of pre-training, yes. It is definitely possible, in training and in fine-tuning, to make a LLM resistant to engaging in the role-playing requested in the prompt.