I have noticed a number of sims dying in my sims' presence - far more than you would expect from random chance. I once had an opportunity to deliver something to Anna-Lize, and as soon as I gave it to her, she croaked. Now, maybe the opportunity was keeping her alive, but a number of other sims have died immediately or shortly after visiting my sims, or my sims visiting them.
Whether it's a bug or something else, it makes me wonder if showing up somehow does something to the odds.
Goat