What we call "liberalism" is not substantially more willing to question its beliefs than what we call "conservatism".
People who fall under the American political label "liberal" are almost as ideologically entrenched as those who fall under the label "conservative"; they just happen to stick to a slightly more modern set of arbitrary beliefs.
The people who really question the current political environment are almost always labeled as ideological extremists, which American liberals certainly are not.
Now, as for science, it seems to me that liberals are just as liable to believe in the stereotypical anti-GMO anti-gluten pseudoscientific rhetoric as conservatives are to believe in the stereotypical anti-evolution anti-climate-change pseudoscientific rhetoric.
I still don't like how the article values that in a negative way.