I don't think anyone should be forced into doing something they don't want to, but if you let odds like that effect your life, then I think there is reason to suggest that there is an issue there that should be looked at.
I certainly don't think 'more power to you'. A choice based on information is a good one. One based on fears or misinformation, not so much. Still someone's choice to make, but still a decision I'll continue arguing with.
When I see someone state a position like that, my presumption is always they're either ill informed or misinformed, and when it comes to HIV there is a lot of misinformation out there, so I'd certainly never blame anyone for falling victim to it. But I wouldn't just send them back on their way without trying to shine some light on the reality of the matter, even if that reality is 'you are letting your fears make you irrational'.
If you refuse to fly for fear of the plane crashing, I will try to show you that it's not a rational stance to take, and try to help you get over it. I'm all for safety demonstrations prior to take off though. If a potential partner of mine informed me they were HIV positive, I'd be grateful. Maybe I'd double check the expiration date on the condom packet... but I wouldn't put my pants back on and get the hell out of there, because that's cold as shit.