Yes, it is true that correlation does not equal causation. Have you seen how many girls this Gardasil epidemic has affected? There are some right here in my small city in Japan.
As for duration of immunity, in the MMR, ELISA antibodies were detected as late as 10 - 13 years and NOT ANY LATER. They either did not test further, or found 13 years to be the max length of duration. These are the only two possible possibilities which can be rationally drawn from the language, no?
If they did not test further, the CDC should not say people are "considered protected for life."
We can see this limited duration born out in recent measles outbreaks in nearly fully vaccinated populations, with "fully vaccinated" adults getting the measles.
Correct regarding length of immunity language. I simply pointed that out because your post seemed to imply that immunity only lasted 10-13 years. Based on the insert we really don't know how long immunity lasts and yes there probably should be longer studies.
I'm on the fence regarding Gardasil. I have adolescent daughters and we chose not to vaccinate with Gardasil at this time.