Ehh, given the person we are talking about (Elon) I think that's a little naive. They wouldn't need to add it in the system prompt, they could have just fine-tuned it and rewarded it when it tried to find Elon's opinion. He strikes me as the type of person who would absolutely do that given stories about him manipulating Twitter to "fix" his dropping engagement numbers.
This isn't fringe/conspiracy territory, it would be par for the course IMHO.