This story says yes:

Ynet has learned that 18-year-olds who tell recruiters they play the popular fantasy game are automatically given low security clearance.

"They're detached from reality and suscep[ti]ble to influence," the army says.

I'm not sure how accurate the story is; for instance, a few paragraphs down it says:

"One of the tests we do, either by asking soldiers directly or through information provided us, is to ask whether they take part in the game," he says. "If a soldier answers in the affirmative, he is sent to a professional for an evaluation, usually a psychologist."

More than half of the soldiers sent for evaluation receive low security clearances, thus preventing them from serving in sensitive IDF positions, he says.

"Automatically given low security clearances" isn't the same as "more than half . . . receive low security clearances" (though it's not clear whether the denominator in the latter statistic is all people referred for evaluation, or just D&D players); and this is the sort of inconsistency that makes me uncertain about the rest of the story's claims.

Still, if the story is accurate, it seems odd. Maybe D&D circles have changed a lot, or maybe the ones I was in were unrepresentative — or maybe I'm a lousy judge of who's detached from reality and susceptible to influence. But my sense is that most D&D players are perfectly fine people. Geeks, mind you, but geek is good.

On the other hand, the Israeli military is supposed to be pretty sharp; doubtless it has the normal share of bureaucratic folly, but I'd assume that most of their judgments about soldierly quality are better than my judgments. So, who knows, maybe they're right.

Thanks to Dylan Alexander and Michael Koh for the pointer.