This is true regardless of whether the "things you can't say" are true. Furthermore, the whole contrarian/red pill/pretty lies/uncomfortable truths meme is toxic. It's a death spiral. All opposition demonstrates your superior insight, and all agreement demonstrates your superior insight. Everything demonstrates your superior insight, which together with the normal repertoire of human biases makes it pretty much impossible to encounter any evidence that you're wrong.
There are no red pills, only blue pills with red sugar coatings.
This is true regardless of whether the "things you can't say" are true.
Not quite. The joke is more likely to resonate with the audience if it corresponds to their experience.
Nevertheless, I agree that the joke is no substitute for an argument. It's necessary to get society to the point where it's possible to make the argument without being declared unfit for polite company.
As Multiheaded added, "Personal is Political" stuff like gender relations, etc also may belong here.