I'm not sure that's a compelling argument.

In both these cases, individuals are talking about broader societal trends. It's not a contradiction if they aren't talking about their own specific experience (i.e. "I'm silenced, therefore I can't talk, listen to me talk about how silenced I am"). An 18th-century writer discussing sex may contribute to the counter-argument that by virtue of their writing about sex, it isn't as taboo a subject as they imply. But in and of itself, it isn't proof that such a trend does not exist.