Earlier quoted context omitted.
Arrows theorem simply doesn't apply here. We don't need our personalized search results to satisfy the majority.
But in both cases you face the problem of aggregating preferences of many into one. In one case you are combining personal preferences in the other case aggregating ‘preferences’ expressed by search engines.
Conditions the mixed ranker doesn't have to satisfy "ranking while also meeting a specified set of criteria: unrestricted domain, non-dictatorship, Pareto efficiency, and independence of irrelevant alternatives"