Ridiculous and irrelevant. The "respondents" defined WMD as NBC weapons, meaning they believed there were NBC weapons in Iraq, which there were not. The OP's point that these respondents are out of touch with reality therefore stands.
The distinction here is of course critical, because not only did they believe something that was not true, but they believed the allegations of the Bush administration, who repeatedly claimed there were NBC weapons in Iraq. In other words, they continue to be suckered, even up through today, even AFTER the Bush admin itself has repudiated these allegations.
I think a great deal of what we see from "Conservatives" has to do with fragile self image. On the one hand, their faith based commitment to identity politics makes them clay in the hands of expert propagandists, and on the other hand they're desperately afraid of being suckered. So when they have been suckered, they can't admit it, even to themselves, because they'd feel shame & inadequacy.
Which just makes them more susceptible the next time.
What few Liberals or Progressives understand about modern Conservatives is that it's not about facts, or knowledge, or reason or anything like that. It's about identity, and about Faith. They've been taught since childhood to Believe- in Jesus, in Capitalism, in conformity, sanctity, loyalty, work, (some of which is quite admirable) in the inherent goodness of those who espouse what they've been taught to believe & to emulate. So when the figures & the ideas they believe in fail to deliver, they just keep on believing, anyway. Never looking at what they believe & why they believe it is the easy way to cope, and if what they're being told makes them feel good in some fashion or another, even a perverse fashion, they'll just enjoy the feeling.
Their leadership understands them perfectly well, plucking at their strings the way that Robert Cray plucks the strings of his guitar. That guitar can't play itself, isn't self actualizing, and neither are they.