Shareholder ROI is all you need to know that they won’t let Norvig decide anything outside purely tech stuff.
Or the executive/management team could start using Google search themselves so they can see how bad the results are for their users. Pretty common to dogfeed in the software business yet Google seems to ignore this approach.
What search engine do you think management uses now?
They probably use some internal version that doesn't optimize for ad revenue but instead for user experience, as is Google tradition.