Perhaps they are now put in a position to consider peak oil as a possibility.
This is scary for them. As a consequence they have to leave their "just don't think about it..." position. From there it is easier to trash the idea aggressively rather than think it through.
I have also found the same thing. Friends of mine who turn out to be most conservative find these ideas (and especially ideas about the actions of the US government) downright offensive. They then prefer to attack me after a piss poor defense (they generally fall back on CERA and Popular Mechanics saying that these organisations are the best in the world and would not lie!).
We had these discussions when oil was at $US 80 a barrel. It was claimed that $80 was an anomaly and will now retreat back down to $65 (these guys are economists BTW).
I sit back and wait. Once reality demonstrates the concept (as it is doing), they can observe for themselves. At which point we can return to the debate.
Dr Bang

For every question , there is a lie. For every lie, there is a truth. For every truth, there is a way. And for every way, there is a time. This is the time.