The problem with pedophilia isn't that it's offensive, it's the harm caused. As you well know... If you can make a good case that soydev memes are as bad as, you know, molesting kids, then please do.
The point about niceness is that agreeableness alone isn't indicative of morality. The bureaucrats managing the death trains were as agreeable as anyone. Niceness is nice to have, and some degree of agreeableness is needed to operate in society, but niceness for niceness' sake is just vapid. Successful sociopaths are nice. Niceness, politeness, these are all social ceasefires/tools. Nothing wrong with that, but they shouldn't be the fundament of your personality- there should be something more to you than "I'm a nice guy". And "I'm a nice linux nerd" just sounds especially vapid.
If I met you in real life, I'd be nice and polite (according to the social rules of our current culture), of course. And LS is being nice and polite according to the social rules of /g/ culture. That space isn't really meant for you and doesn't have to conform to the rules of politeness of mainstream culture, much as you wouldn't go into, I don't know, a punk rock concert and ask them to tone down their language a bit. Would you deny these weirdos their safe space, where they can joke about wagecucks and gnutards? That language was born of attempts to be edgy, yes, but once it became fixed it was no longer mutually offensive to interlocutors.
Ironically, you're being more interpersonally combative/abrasive than anyone I've seen on LS's channel! Less nice, in other words. With your attitude, and your sailor's mouth, you might belong on 4chan, after all.