Because not every project is headed by Linus Torvalds. That man has almost no filter (which in my opinion is a good thing).
However, that same type of stuff may not reflect other organizations and members of those organizations in a good light. So there are definitely concerns there.
I'm a developer, and my company's closed source code definitely has its share of profanity and "WTF"s. But that would not fly for things we make available on GitHub, just due to concerns of our image. Most developers wouldn't give two shits about the comment...
Do you honestly believe that there would be any damage to your company's image that would last more than 5 seconds to a small minority of people that would even see an article regrading "improper language"?
Unless your fellow developers are posting extremely obscene racial slurs and threatening rape on the interns. In which case your company has bigger issues to worry about.
However, that same type of stuff may not reflect other organizations and members of those organizations in a good light. So there are definitely concerns there.
I'm a developer, and my company's closed source code definitely has its share of profanity and "WTF"s. But that would not fly for things we make available on GitHub, just due to concerns of our image. Most developers wouldn't give two shits about the comment...