Is this a "sexist and misogynist taunt", or have feminists lost all sense of humour?

Okay, would he have told another man to "calm down dear"? Of course not. If he had just told her to calm down, that would've been fine but don't add in a cutsie, demeaning name just because she's a woman. And I don't think that comment was meant to be funny, so I don't see how a sense of humor would be needed to be okay with this.