1) where did you get the idea that HH fucked her. She was in his magazine, not his bedroom...
2) Playboy at 18, diagnosed at 22. She did playboy before she caught HIV
Actually, I believe the article linked to the pic said that she caught HIV from unprotected sex in high school. So she was apparently carrying the virus several years before being diagnosed, which is not at all uncommon.
Even if Hef did have her tested at 18, and she had tested negative or false-negative for whatever reason (not unheard of either - especially early on), and he did shag her without a rubber - female-to-male transmission of HIV is far more difficult than other STDs. Odds of him NOT contracting the virus would have been far in his favor according to experts. Still, I would not want to play those odds myself.