This is a genius idea
This is basically a licence to print money - it's a great idea by ICM.
Porn operators aren't actually interested in the domain, as it's far too simple for *.xxx to be blocked any number of ways, so their potential visitor base is reduced. Instead, by simply saying "Nice .com you've got there, be a shame if anyone registered the .xx version of it, wouldn't it?" ICM get a decent wodge of protection, I mean "defensive registration" money, and it doesn't matter how many .xxx domains are actually registered.
Obviously the knowledgeable types - i.e. us lot - wouldn't bother paying up for this as we know there's no point, but that doesn't matter - it's not us they're after. It's the managers, the brand owners, the PR departments - all of whom will say "Oh, it's only a few hundred bucks? Just do it".
So, who's up for registering .sex next?