Firstly there is a strange misconception that posts are flagged based off being "offensive".
This is not the case, posts are flagged off being off-topic, inappropriate or otherwise against the forum guidelines. The guidelines and the Discourse software are all are crafted with the focus of creating an environment where everyone feels free and eager to participate in great discussion.
A guaranteed way to ensure that doesn't happen, is for forum members to assume that they're above the rules and that if they do something and people don't like it - they should just double down and make it everyone else's problem. That's what Amir is doing in that thread, that's why I linked you to the thread I made on "so your post has been flagged". As you can see, Amir is pretty much just concerned with getting the last word.
It is true that perhaps many people don't get the sarcasm, that's not their problem. Text is a limited medium and when you post in it, you need to respect that just like you need to respect things like you're posting on an international forum, the forum language is English, spoiler tags, etc.
The other guaranteed way to choke quality conversation is to flood the threads where people are trying to talk with bullshit, derail into off topic territory, troll people by bringing up topics you know are pet peeves, etc. This is why there's a flag for off topic and "other". Motivations for doing so can range from deliberate malice to people simply assuming it's The Internet so there are no consequences and they want to act up like they're afraid to in everyday life.
This is not a matter of a little side joke in a thread, a reference to a fellow forum member, etc. And if you do get a flag for that because your'e going off topic etc, it's pretty easy to go back and edit your post. You can create a new thread or post in another thread and link to it, you can decide your post didn't contribute anything and just delete it etc.
It contributes to the forum, makes things good for everyone and sets a good example for new members. This last aspect is particularly relevant when in less than two weeks we are expecting a massive slew of new members - and the moderating staff doesn't want to be spending all their time sending messages in response to "but what about when ... did it" - believe it or not, we'd like to have time to play the game too.
Flagging happens more often than warns or other types of feedback in other software because flagging is easily dealt with by editing your post - you have the power to fix it.
It is my sincere hope that it will mean that I spend a significantly less amount of time going through and digging through otherwise good threads to remove attacks at members (and IO-Interactive), random BS, office topic BS and personal fights in public places than I did when Absolution came out.