You can't really compare a search engine to a site like TV-links. A search engine doesn't discriminate in what content it indexes. If a search engine would only link to copyright-infringing material, then that search engine can expect as much trouble as a site like TV-links.
If a site mainly exists to facilitate copyright infringement, should it get a pass?
If dealing drugs is against the law, what is directing people on the street to drug dealers?
Things like changing link destinations are interesting from a technical point of view, but not all that relevant to this case IMO. If the site was a chatroulette for online links, this might come into play, but for TV links to have a changing link, in all likelihood it meant simply a broken link.
Indeed, most of this boils down to intent. Pointing people on the street to where they can buy drugs or selling them pipes to facilitate drug use, to me, it isn't the same as dealing the drugs yourself. But I can totally see you can find yourself on the wrong side of the law, when you start facilitating illegal activity.
Again, I agree that linking to content should always be possible, but I can understand where the law and entertainment industry is coming from.