...conservative/evangelical/fundamentalist/extreme-sectarian Christian...
That is quite a sub group. Are all of those attributes required to apply?
Is my assessment of... education accurate?
I went to a Mennonite high school for 3yrs. They were fairly liberal in that they dressed normally, had zippers and drove cars but no dancing. A sense of community and common faith permeated everything but there was no willful denial of facts on an institutional level. Evolution was taught and any conflict was discussed in religious studies class. This is where the willful denial showed up and it manifested on a personal level.
I think that your assessment is accurate. Perhaps not across the board but more about the way that most individuals of faith approach their own education. As a result it shows up in the way that they run their schools.
So, why the willful ignorance? Fear of the unknown and a reliance on what has worked in the past.