There is a hack over on the german hack site tht restricts it from showing in the box for new threads and in the popup but the image still parses in posts for those not allowed to use that smilie.
I wish it would parse as like a red x or a censored smilie or even %%%%%% symbols.
This would be so awesome to implement and I hope someone is able to do this
I personally would use it for an adult secondary usergroup I have that gives them access to a rated R joke area and then they'd have some of the more crude smilies they could use everywhere but to those not in the secondary usergorup it would show up as %%%%%