I think the dad is reeling, and whatever it was would make the son look bad. With all the rumors I would imagine the dad is trying to protect his son - after death. I'm sure there's guilt that he didn't see what was going on.
Curious as to why the mom hasn't spoken out.
It would be interesting to see what she says.
I agree, though, that dad is trying to cover for his son. But who (or what) is Dave Boren covering for?