This is a real problem. The situation isn't exactly analogous to a salary negotiation though. The balance of power between reporter/PR guy is much more equal than between employer/employee. Yes, if she encounters that guy again he might think that she's "that bitchy reporter", but he's still going to want her to write positively about whatever game he's promoting.

If he has even the slightest idea of how to do his job, he might appreciate the insight into how to make the demo the best possible experience for her. There's a good chance he walked away thinking "I sure did a good job showing that lady reporter how to play our game".