I can't seem to find any data which suggests that Liberal Arts majors are significantly more likely to fall for climate change denial or the anti-vax movement. I find that most studies correlate political leaning with these beliefs, not area of study. Given that the Liberal Arts are overwhelmingly liberal in the US, I'd say your claim is probably wrong.

If anything, a Liberal Arts educations ought to provide students a higher degree of skepticism towards all expressions of ideology, and seek to find the truth through critical research. Obviously, that's the ideal, note necessarily the reality in all cases, but it seems your notion of Liberal Arts is more akin to "hippy-dippy" nonsense, not critical study.

>Liberal Arts majors should be required to take more science courses

They are, that's the point of a liberal arts education:

https://college.harvard.edu/what-liberal-arts-education

>In our liberal arts program, students are broadly educated in the social sciences, the natural sciences and the humanities, as well as trained in a particular academic field of specialization called a concentration.

https://admission.princeton.edu/academics/what-does-liberal-...

>By exploring issues, ideas and methods across the humanities and the arts, and the natural and social sciences

https://www.aacu.org/leap/what-is-a-liberal-education

>It provides students with broad knowledge of the wider world (e.g. science, culture, and society)