Why would a man lower his eyebrows in maybe disaproval if a woman does this?

Couple of reasons....One is the one you mentioned where he is questioning their authenticity of her insecurity, but not because he finds her attractive. Its because people who genuinely have those insecurities, generally wouldn't talk about it. The other reason is because he thinks she's all too eager to present herself as a victim. And as a man....He can't respect that.