Statistical analysis aside, I think this is the key sentence. the writer cannot conceive of young adults abstaining from sex or alcohol.
If you're making a general statement, yes, I agree with you: Media coupled w/school leaders oft communicate a cater-to-the-lowest common denominator of "everybody's doing it." And they oft' can't fathom a large % of students remaining abstinent from sex & alcohol.
Still, you can't 100% lay aside the "statistical analysis," because the author did cite "over 30,000...young adults" -- and in that sense, he's statistically right: All over 30,000 young adults going to 100% abstain from those two activities? (Don't think so)
Heck; NO one can - if they be abstainin'!