The study says: "“It’s not enough that men, on average, score higher than women on a scale of masculinity,” Carothers told Raw Story. “Nearly all of the men would have to score higher than nearly all of the women on nearly every item of the scale. We did not see that level of consistency with the psychological variables we had.”
So, if you decide that an average score of masculinity or femininity is significant, then this study considers your approach invalid.
This study appears to be saying that no one woman can be presumed to be less masculine than any one man, for instance. Fair enough. But as it proceeds from the basis of there being 'masculinity' and 'femininity' in the first place, there must be something to the idea of psychological gender difference - at least on average.