This approaches one thing I always wonder when this comes up: Are people with that argument really okay with their co-workers finding out what porn they watch and when they watch it?

It's perhaps a little extreme, but I can totally see it becoming a possibility due to large leaks like this.

Regardless, I disagree with the argument, as things you don't need to hide now can become things you wish you had hidden later (think of Jewish people in Germany in the 1920s whose religion and ethnicity were obvious).