The idiom like Caesar's wife is mentioned in the book 1100 words you need to know (Murray Bromberg and Melvin Gordon, 4th edition), and used in the following sentence as an example:

Mrs. Drake would have to be like Caesar's wife so that no tinge of scandal would embarrass her husband, our new mayor. (page 134)

I'd like to know if such idioms that are verbally suited for one particular gender can be acceptably used for the opposite sex as well. To my non-native way of thinking, and considering the definition of idiom (i.e. an expression in the usage of a language that is peculiar to itself in having a meaning that cannot be derived from the conjoined meanings of its elements - Merriam Webster's- 11th edition), the opposite-sex usage sounds non-problematic as long as an idiom- and not a proverb- is used. Any ideas, please?