The article confirms that Professors tend to be "lefty" (liberal, identify much more with the Democratic party, or however you want to say it). It also confirms that college-age is the part of the life cycle when people become especially lefty in their politics. But it questions the conclusion that college-age people are adopting their Professors' lefty views.
I agree that it is easy to exaggerate the effect of Professors' political views on those of the students. Like almost any market, the marketplace for college education is competitive and thereby serves the interests of its customers. That is, marketplace for college education has outcomes that reflect the interaction of supply and demand!
If the college students, their parents, and their employers all did not want the students to be exposed to a parade of lefty Professors, then an entrepreneurial college would stand to make millions in tuition revenue by putting some not-so-lefty Professors out there. The schools that stuck by their lefty-ness would see dwindling enrollments.
Even if there were not as much as one among the thousands of colleges that was so entrepreneurial, there could still be a department that might dare to house a Professor or three who were not-so-lefty (in order to protect the innocent by refusing to name names, I will amorphously refer to that department as the "Economics Department"). If supply and demand had any predictive power, then we could be sure that the Economics Department would attract students -- and recruiters from the world of employment -- at the expense of departments that refused to recognize their consumers' situations (again, to protect the innocent, I will refer to the latter departments as "Humanities Departments").
By these kinds of mechanisms, Professors' political views reflect the situations of their students, and not the other way around. Humanities Departments are in really big trouble if many elderly ever enroll in college (that is, Humanities Departments should not expect to be acquired by business schools)!