Chances are that he was taught that because there are no competing theories. Try as I might, I cannot think of a competing scientific theory to evolution. There is, of course, Intelligent Design but it isn't science as it has no testable hypotheses. Even Paul Nelson has admitted that there is no theoretical base behind ID. There is always progressive creation, but, once again, there is no way to test that except to show that organisms have changed over time in some way. Given the nature of the fossil record (especially in equines and hominids), choosing progressive creation is a step in faith because there is a known mechanism that exists to explain the changes in the fossil record, namely biologicalk evolution. I am waiting to see what alternative theories he comes up with. As Kenneth Miller says about alternative "theories":
As students step foot on campus for another school year, an intelligent design proponent has offered a few tips for the millions who will face the teaching of evolution in their science classrooms.
Tip number one, “never opt out of learning evolution,” says Casey Luskin, co-founder of the Intelligent Design and Evolution Awareness (IDEA) Center, according to the Discovery Institute.
“In fact, learn about evolution every chance you get.”
Having attended public schools from kindergarten through his master’s degree at the University of California, San Diego, Luskin was taught a “biased and one-sided origins” curriculum – basically, the neo-Darwinian theory.
“It is possible to come up with any number of possible explanations for anything—lost socks could be caused by extradimensional vortices which our observations prevent from forming; hiccups could be caused by evil spirits inside us trying to escape; stock market fluctuations could be caused by the secret manipulations of powerful extraterrestrials.Scientists reject such claims on the grounds of parsimony. All of those claims are possible, but they require adding complicated entities which there is no adequate evidence for.To make matters worse, the nature of those entities effectively prevents investigation of them, and the impossibility of investigation prevents us from learning anything new about them.We cannot conclude that any of those explanations are wrong. But from a scientific standpoint, they were worse than wrong; they are useless.”1See the post on exaptation for an example of this. What Luskin is advocating isn't bad science. It isn't science at all. If there were legitimate alternative theories to evolution, it would be different, but there aren't. Wishing there were doesn't change things.
1Miller, Kenneth. (2008) Only a Theory: Evolution and the Battle for America's Soul. Viking Adult. p. 11