I think as long as there is a warning about the foul language involved in the link, they shouldn't mess with it. I have posted links to stuff in that way & haven't been bothered.
Speaking as a moderator, you're partly right - we do have leeway to allow some links under that condition. It depends on the context, subject matter, and how extreme the language is. The relevant section of the forum code of conduct is:
Avoid directly linking to disallowed content off-site. We will be a bit less strict about content in off-site links if there is a content warning in the link, but there are still limits to what you can link to.
This one can barely slide, as long as there's fair warning. But please don't take this as an indication that a warning will always make a link okay, or that videos with this much inappropriate language are always okay. Each situation will be different.
If you have any doubts about a link, please ask a mod beforehand and we'll get back to you as soon as we can.