What they could do is build in technology that recognizes offensive terminology and refuses the comment or opinion. Or, they could build in a rule that recognizes terminogogy related to sexuality and produce a warning that the question does not have a sexuality topic. And, honestly, moderators are humans... we judge whether a question, opinion or comment doesn't respect the GAG policy. But we can only hide it. It's the admin team who decide whether to remove it or not. So there is a double check. We cannot randomly target 1 user and remove no-matter-what, we should be fair in that.
GAG does delete comments that break the rules but I think they rely on us reporting them. The mods can not go around searching every question for comments that should not be there if they did that we would be paying to use this site. I reported some very very nasty comments from a girl that broke the rules and they were removed.
yep, its one of the moderators jobs to find them and report them so the admins can quickly respond to it, everyone with an [m], [u] or [s] before their name is a mod, in my opinion its good that nasty questions and comments get removed because this site doesn't support incessant flaming, theirs a difference between having a friendly argument or heated debate and having an outright rage rant.
also to clear something up, mods don't get to delete comments and questions, admins do, mods simply speed up the process by reporting and hiding them, the admin's decide what to do next, mods can't simply flag anything without valid reason.