Moderators are people, and as such we all have our own biases. While I think it's important to try to keep your personal biases in check, I imagine that some people make an effort to do so, and others might not. Moderators have the ability to hide posts that break the rules, and then the admins make the ultimate decision to remove them.
There are far more moderators than admins, so I imagine that most of the questions and comments that are removed are done so either because a moderator has hidden it or a user has reported it. If neither of those things happen, it's unlikely that an admin will know about them. Also, even when things are hidden or reported, it can take some time before admins get around to removing them (for example, in the past, I've tried to hide things and been told that they were already marked for review or that I myself had already hidden it at some earlier point in time).
The rules that we are given are, to be honest, pretty vague. They leave a lot up to the moderator's discretion, which is good in some ways, but also leaves even more room for people's personal biases to come into play.
In my personal opinion, both of those comments should be removed. I would consider yours to fall into "Offensive" and the other users' to be "Antagonistic".
The posts that contain content that is insulting, degrading, distasteful, and/or irrelevant. Healthy debates are encouraged, but racism, sexism, and blatant personal attacks and/or insults are not.
Example: “Black people should all be killed.” “I want to rape and kill all women!”, “You are stupid”"
While we encourage lively debate, posts that bait, antagonize, or lack a genuine question should be hidden.
Example: “I hate all Christians. Here’s why.”
Example: “Democrats/Republicans are all idiots and lazy. Do you agree?”"
A charitable view of what happened in this situation is that your comment was a "blatant personal attack", but the person hiding it may have been unsure whether or not the other comment should be removed (I'll admit that while that comment seems pretty clear cut to me, there are many others that I feel unsure about---it can be difficult to find a balance between allowing for open discussion about sometimes controversial topics, and making GAG a welcoming place where people feel comfortable engaging in discussion).
A less charitable view is that the person has a bias against feminists.