Perhaps the solution would be personalised weightings for search results. You could then build a weighting graph based on blacklists, e.g. if I have a pro-abort

Perhaps the solution would be personalised weightings for search results. You could then build a weighting graph based on blacklists, e.g. if I have a pro-abortion site on my list and it's found on someone else's blacklist then I would have a negative weight for the other sites on their blacklist. Maintaining the graph and weightings would be massively expensive though so I'm not sure when it would be viable.