Well, first of all, if you go to a third world country for vacation, you ought to have your head examined. These crimes have been publicized all over. If you don't know about them, you aren't paying attention. And if you know these places are dangerous, but you go anyway, then you're a moron and I don't have any sympathy for you.
Next, TripAdvisor probably has no way of knowing whether allegations of rape, robbery or other violent crime are true. There are people who troll these review sites posting phony reviews trashing hotels, restaurants and such either just for the hell or perhaps because they have been retained by rival facilities trying to stifle the competition. TA tries to identify and remove phony reviews and maybe that's what they are trying to do here. At the very least, TA should try to contact the reviewer and ask for some verification of these allegations before the review can be posted.
I'm not a shill of TA, although I have consulted the site for reviews and recommendations and have found the site helpful. I would like to hear their side of the story, however.