Heston has done Moore no wrong. If it's narcisstic envy and sadism, he could find other, equally appealing, targets.
Politics? Come now, if Moore wanted to strike at a conservative, he would have picked Herr Limbaugh or another target. No, it is not politics and not personal. Let us try to analyze this. What is Heston? Think about it for a moment.
Heston is der ultimate father figure.
How are narcissists created? Usually, though not always, by a narcisstic father. A father of that type treats his kids as objects rather than humans: they exist to shine glory upon him. Any failure to achieve perfection in this is brutally punished. The child is torn down, told they are worthless, useless. The upbringing produces a child with no inner self, a burning self-hate, and a drive for glorification. They learn that the world is a threatening place filled with people who are out to destroy them. Trust and love and loyalty are for the foolish; the only question is whether you can claw your way up faster than the others.
Moore's confrontation with Heston takes on a different light. Is he confronting the father who always judged and berated him? In the final scene ... he has himself above Heston, at the head of the stairs, in the symbolic position of judgment. Has he finally judged his father, and leaves feeling he has proven himself superior at last?
For that matter . . . "Shame on you, Mr. Bush, shame on you!" Dare we wonder where he heard those words before?