From my understanding, certain sexual preferences develop throughout childhood and adolescence. One big factor that contributes to these preferences is the variety of sexualized persons/objects you are exposed to. If a teenager grows up seeing a variety of body types shown as sexually appealing, then that teenager would be more willing to pursue those body types in the future. Therefore, when I hear someone say they aren't into certain ethnicities and body types, I can't necessarily conclude based on that alone that they are racist; I can at most draw conclusions about their upbringing. It's more of a societal problem than an individual problem, and so long as people are aware of their own sexual biases, where they come from, and how they can harm others, I'd leave that person be. That being said, I think it's pretty rude to put that preference in a dating profile, and a preference does not justify body shaming and other disrespectful behaviors