Is their preference really any more arbitrary than the preferences sapiosexuals or demisexuals have? It sounds like they probably have other traits that may make someone more or less attractive, they just have a minimum requirement for a certain body form for them to begin having attraction. That isn’t so different when compared to a sapiosexual who requires a high intellect before they can begin being more or less attracted based on other traits.

TL;DR: All preferences are weird, no need to call anyone out on their specific ones :)