Is there a large percentage (or even a measurable fraction) of hams "who think women or young people should not be on the radio"?

I think you have to go back several decades to the legendary W2OY (with aplologies to the current holder) to find a single visible example of that attitude.

As a member of multiple minority groups (Native American, Hispanic surname, non-Christian religion) I'm sensitive to discrimination and harrassment issues. My long and enthusiastic association with amateur radio is in large part due to my complete acceptance within the hobby without any regard to my ethnic roots, skin color, or religion. Neither have I seen anything but complete acceptance of young people and those of the fairer gender in the hobby. If the general population were as tolerant of diversity as I've found the ham hobbiests to be, this would certainly be a nicer place to live.

Thus N2EY's suggestion (if that's really his point as you surmise) that young people and females would do well to mask themselves behind keys/keyboards to avoid unpleasantness is ludicrous on it's face, and might be construed as a projection of an unrevealed agenda of his own.

The Man in the Maze
QRV at Baboquivari Peak, AZ