Used in a science curriculum, you're studying the science, and may as well get rid of distracting elements. Bowdlerizing it in the context of a language arts curriculum would still be "in schools", and I'd go the opposite direction there. In that context, I'd say they're an important part of the book, establishing the character that the author wanted to portray, and that you'd be losing lessons on contextual appropriateness of different registers of language.

The fact that both situations would occur in a school setting is completely irrelevant to me. I don't think that it should play a part in the "abridgement" decision (although I recognize that it would, and that my opinion on the matter is likely to be controversial). It's more important to me how closely it fits the purpose that it's being put to. In the case of my two examples, scientific vs artistic truths.