I don't think this is necessarily a reflection of HN's biases.
Rather, there is simply little new to be said about this in a vacuum: yes, there is a problem with sexism and yes, the reaction to her project is disgusting (regardless of your stance on the issue) but all that is clear from the article. What more to say about it? I suppose people could offer sympathy--certainly a nice gesture--but not with much substance. Since she probably does not read HN, those types comments would not be very useful at all.
So most of the people agreeing with the article do not really have a good reason to post at the top level. On the other hand, they have plenty of reason to respond to other people. So the sympathetic posts are all framed as responses to others' comments largely because there isn't much to respond to in the article.
Rather, there is simply little new to be said about this in a vacuum: yes, there is a problem with sexism and yes, the reaction to her project is disgusting (regardless of your stance on the issue) but all that is clear from the article. What more to say about it? I suppose people could offer sympathy--certainly a nice gesture--but not with much substance. Since she probably does not read HN, those types comments would not be very useful at all.
So most of the people agreeing with the article do not really have a good reason to post at the top level. On the other hand, they have plenty of reason to respond to other people. So the sympathetic posts are all framed as responses to others' comments largely because there isn't much to respond to in the article.