You keep assuming the negative in your mindset.
causal link between the behaviour of the woman and the behaviour of the man.
"be nice to others and others will be nice to you" is literally what it is saying. That is it. No need to imply anything or add words or nuances. That is it.
If I see the phrase... The more you act like a gentleman, the more she'll act like a lady.
I wouldn't be offended in the slighest nor should any man be. It is ridiculous people are and making the school take it down.