While I find it more than a little detestable to ask someone if they were abused/molested, this is actually a commonly enough referenced occurrence that it's entered the realm of pop psychology. I imagine anyone who watches Dr. Phil or Oprah is familiar with this concept. But fat feeling "safe" does not automatically imply "safe from rape/incest/molestation."
Back in the real world, there are an innumerable amount of reasons someone's fat may make them feel safe. I personally feel that way, and part of it is that it wards off unwanted attention and advances, but not because I'm afraid of men as a result of sexual trauma. I just like that being fat allows me to attract men who prefer me in my true and happiest form - fat
.
In addition to helping me siphon out the (hopefully) more genuine men, it also protects me from being bothered by the other kind hitting on me. Yes, one part of me enjoys the flattery, but that style of advance has nothing to do with what makes me "me," so how flattering could it possibly be? I don't get it, I don't like it, and I really dislike being objectified (until we're on an intimate level, and in that case, by all means, treat me like your sexy piece of meat).
The point is that we all have a psychological relationship with being fat, and with the impact our size/shape has on our place in society. I like the fat side of life for a lot of reasons, and it's a shame that someone is using a concept they saw/heard somewhere in the media-ether to draw assumptions that they are in no way qualified to make.
If it ever comes up again just explain that a fat person is less likely to suffer serious traume if they get hit by a car. Why wouldn't our fat make us feel safe?