[mooman219]

This. The web host is likely going to try to spoof a low load time by sending a fake page to Google's web crawler. Then it'll be an endless cat and mouse. Also, there are more than a few websites on the internet. It sounds fairly unreasonable to keep fresh numbers on page load times.

[TurningCanadian]

They might be able to crossreference the result from their crawler with metrics from Chrome users that opt-in.