Not all offensive intent is created equal.
The use of a term such as retarded to refer offensively to another person (usually to someone with whom I disagree, but can not effectively explain why they are wrong) actually should not be offensive to the clinically retarded any more than the use of the term weakling is offensive to the clinically weak.
The intended offense is not to the “real” retarded – it is to the person whose arguments I find so preposterous that I would label them (him?) so irrational as to be “retarded”.
The fact that some people who have clinically retarded relatives can be hypersensitive to the use of the term nevertheless does not confer “offensive word” status on the term. (Notice “some people” – I have close family members who are clinically retarded, and have no problem with the way the word is used).
I think we all agree that the word cancer ( as in, “talking in shul has spread like a cancer”) is not offensive. At the same time, I think we all appreciate the value in choosing a different word when cancer patients are nearby.
The only question is, to what degree must we be wary of the possibility that an affected individual may be hurt (not offended!) by its usage in a particular setting? (in the CR, this is very likely…)
This is very different from, for example, the N word, which has evolved into an offensive term with a very negative connotation.
Just ask Joe Biden about such words.
As an aside, I do think that rape is the correct translation of me’anes. As PBA pointed out, although the definition of “minor” is different in Halacha from US law, the definition of “consent” is about the same. We find many times (as in Parashas Ki Savo) where explicit terminology in the Torah is masked as an expression of the refined mode of speech which we are expected to employ. I do not think there is anything “wrong” with using the word rape, but that it is uncouth in mainstream “yeshivish” culture (there you go using offensive words again…).
As a Rebbe in an upper elementary classroom, I would never use the word rape. I want to model what I consider to be refined behavior. I do not shy away from teaching any topic, but it is important to teach at all times with the goal of training students to be B’nei Torah.