While you are correct (IMHO) to question the use of masculine and feminine to characterize these sets of words, in the end that is not actually relevant to the

While you are correct (IMHO) to question the use of masculine and feminine to characterize these sets of words, in the end that is not actually relevant to the result. That is, if the authors had called the sets "cooperative words" and "aggressive words" instead, the result would still be interesting. I suspect the authors chose masc/fem to describe the words because that makes for a more click-baity headline for the paper. Not so that it would peg the irony meter of people who notice that they are using gender stereotypes to characterize words in a paper ostensibly written to help reduce sexism.