The problem I see is that you can't really trust a search engine providing links to hidden services. Since hidden services doesn't really use "understandable" domain-names it's very easy to duplicate a website.
What is to say the owner(s) of the search engine isn't targeting journalist and the link to the newspaper I found is a dupe of the 'real' site?
This is by the way a problem in general with hidden services.
The larger internet has the same problem - duplicate content farms, making the "original" of a piece of content hard to discern. It's certainly not a solved problem but by tracking which copy is seen first, using links to imply trust, etc, a reasonable search can still be provided. You'll never have 100% accurate attribution, but that's kinda the point. And when it comes to trusting the search provider, well, how do you choose now beyond seeing consistent result quality?
Agreed trust is a problem with hidden services in general, but I think it's one we'll solve by reframing what it means to 'trust' a site in the first place.
What is to say the owner(s) of the search engine isn't targeting journalist and the link to the newspaper I found is a dupe of the 'real' site?
This is by the way a problem in general with hidden services.