Is “shrill” gender-coded?

The Dish recently quoted a correspondent who, on his or her way to making a point about Chinese tourists wrote

This all has a cogent economic explanation. Paul Krugman, before his current role as shrill liberal attack dog, used to explain…

I found this comment irritating, for reasons that were not immediately clear to me. I have enormous respect for Paul Krugman, both in his earlier incarnation as a populariser of economic theory — particularly trade theory, but also macroeconomics — and as a blogger and twice-weekly columnist who occasionally veers away from economic issues. I think he has a healthy appreciation for his own intellectual strengths, but that he mostly stops short of egotistic attachment to his pet theories, whether defending past statements or being overly sure of his predictions. But I can’t say that there is no basis for someone to think that his tone is overly aggressive, that his political analysis is weak, that even his economic analysis may be distorted by political wishful thinking or antagonism. Those aren’t my opinions, but they’re widely held, and don’t seem to me outrageous.

But what is the role of shrill in that sentence? It’s not a word I hear often, but maybe it’s common in some circles. What does it mean? It’s clearly a free-floating insult, which somehow suggests derangement due to becoming overly emotional, and as such merely replicates “attack dog”. And yet “shrill” seems more contemptuous. What does it mean? Imagine replacing it by strident. It has the same signification with regard to the strength of advocacy, but the contempt is gone. So, is the contempt associated with high-pitched speech? Is this something like bitch, or the dialectical equivalent of “he throws like a girl”? Or is it taking the place of the free-form homosexual slurs that used to be ubiquitous, but are now no longer permitted?