It's not about passing the buck, it's about people being repsonsible for their own actions. Treating people under 18 like they are incapable of understanding those warnings and that they don't have the emotional/mental capacity to make a decision on their own about whether to follow it or not is not only utterly wrong, it's also incredibly insulting to those people under 18. Just under 6 months ago I was less than 18 years old, if someone had suggested then that a completely valid IRC resource should be removed from exposure as a result of that image section because children need to be protected from themselves (which is basically what you're saying by supporting the link to be removed) I would be pretty damn offended. I'm pretty damn offended now as a matter of fact.
I really don't see how your personal moral judgements on pornography or that site (which isn't 'plastered with filth' by any stretch of anyone's highly distorted imagination) have any relevance on whether the site should remain there for the general mIRC userbase to use. Not everyone is so close-minded.