“There is no merit to the suggestion that search results were manually edited.” Right - the results themselves aren't manually edited. There's need to do so,

“There is no merit to the suggestion that search results were manually edited.” Right - the results themselves aren't manually edited. There's need to do so, and of course it wouldn't scale. But if theirs is like any sufficiently featured search architecture we've ever seen -- the training data themselves have been almost certainly curated to favor certain baseline expected outcomes. It's quite likely a good portion of the metadata (read: allow/block lists, in GoogleSpeak) have been manually edited and ranked at some point in the process, as well.