Actually, it makes sense in context to most native English speakers. "To reply in kind," is an oft used idiom. In this phrase "kind" is a synonym for type. It is to say, "to reply in the same way." (Usually in a way which is not kind in the kindness sense.)

http://dictionary.reference.com/browse/retort

I would agree, however, that one, "has no obligation to react to idiotic comments in kind." I hope I've succeeded.