Actually, that’s exactly what it means. The point in question is not whether Mrs. Clinton is progressive, regressive or a lizard person from Mars. The point is that sexism shapes the way people talk about her, even when it’s otherwise legitimate criticism.
Ask yourself if you’d have bothered to write a long reply like that to a post saying the way people talk about Sanders is shaped by sexist gender expectations. Would you? Have you? Is Bernie ever given a free pass on account of his gender? How many in the media, how many voters, and how many activists look at Sanders through some sort of gendered mindset? Here’s the answer: all of us.
Sanders benefits - to whatever degree - from the gender bias in American culture. Clinton is on the flip side of that coin.
Admitting that there is a coin is the first step toward recovery. The next step is acknowledging that gender expectations frame everything Sanders does, and everything Clinton does.