Indeed, using the (query -> result) mapping in their 'Human Web' logs, from other search engines, is a roundabout way of copying both the simple word-to-doc-index, and the complicated ranking logic, of other search engines.

A sufficiently strict intellectual-property regime might find this a copyright violation. But without any inside info, I strongly suspect Google & other incumbents already do similarly-indirect modeling of their competitors' behavior, via extensive query/click-trail mining, in ways that ultimately feed into improvements of their own systems. So, they might not want to press the issue.

Still, this creates a dependency on the competitor you were hoping to displace, where most of your earlier values comes from "drafting" in the easy-path they've already cleared.