That explanation via analogy is actually quite good and may very well be true.

If for some reason memes fail to properly fortify themselves when they claim territory inside your brain, they may be very easy to replace by competing memes, which could explain the "clickiness" of some people.

If true, one thing we may expect from (as of yet) non-rationalist people whose minds have that clicking quality, is that they may be unusually susceptible to New Age crap or generally tend to alter their views quickly. It was certainly the case with me when I was young and still lacked the mental tools of rationality.

Also, a slight rebelliousness or disregard towards what other people think may be part of it. If you ever introduced someone to a position that is very unconventional or even something entirely new that they have never heard of, more often than not they display some deep gut reaction feeling of dismissal and come up with ridiculous on-the-spot rationalizations why that new position can not possibly be the case... and I have the impression, that one of the most determining factors in what their gut-reaction will root for will be heavily connected to what other people in their tribe think.

I know Eliezer's post is older, but I wonder if he probed the possibility that this clickiness may be predominantly a feature of people who simply have a general tendency or willingness for being a contrarian.