If you want to have that debate, then you have to address the concept of insults themselves.

It is the soul of irony to suggest there is a specific line that you're not allowed to cross when you're being offensive, when insults themselves are meant to be offensive.

You can find a bone to pick with any insult. You can't call someone an asshole because there is a significant portion of the population who have either been congenitally born without assholes or who have lost theirs and are using a colostomy bag. And every time the word asshole pops up in their radar, they're reminded of their plight and it is trauma-reinducing.

Calling someone a fucker is potentially trauma-inducing to people who have lost their genitals or been surgically mutilated and are unable to enjoy any pleasure from sex or possibly unable to have sex itself.

And I get that people who have experienced difficulties are different from people who are born with difficulties, but both of those groups are forced to live with things that they simply cannot do anything about. When they encounter aggressive language all they can do is take it.

I still think you are correct that we shouldn't use the r-slur, but we also shouldn't really tone police one another in public when the only method available to do so is to detract from a much more important conversation.

After all, the only way we're ever going to get to a world where the largest concern we have is the Emotional Impact of what words we use when we are angry and frustrated is to deal with the actual world in front of us, where people are murdering and killing people for being born different.