Not odd at all. The "denial syndrome" is exceedingly common on the left. I'm not saying that creationists are leftists. Most of them around here aren't, and would pass out at the suggestion. But deep down, waaaaay deep, there is a psychological similarity.
Consider how leftists during the 20th century had to deny the terror of Stalin, deny the fact that the American communist party was a tool of Moscow, deny that Hiss was a commie, etc. All some weird, sick, very elaborate kind of mental mechanism to deny reality and thus maintain an insane ideology. How much can one deny in order to cling to a fantasy version of the world? There seems to be no limit.
If you have the "denial-type mentality" are there other reality-denying ideological worldviews in which you can find a home? Sure. Lots of them. And being attracted to one doesn't imply any sympathy for the "content" of the others. They're all "intellectually" unrelated. But they all have reality-denying true believers at their core: holocaust denial, moon-landing denial, Afro-centricism (that is, history-denial), and as you noticed, leftists (whose politics and economics are demonstrably insane).
The great virtue of science is that it faces the data without bias, and is unafraid to abandon an hypothesis that is demonstrably false. This "reality-based" outlook is the source of the success of the scientific worldview. Any other "reality-based" systems? I can think of a few: capitalism, the US Constitution (as originally written), and virtually all of English common law.
It really was like arguing with a creationist. He's young and an otherwise smart person so I think he'll eventually outgrow this. Some others are beyond help...