"If Google removed the DNS entry they'd have to reconfigure all of their own servers, too. Not very probable."

That sounds suspiciously like you're saying "I'm going to keep telling everyone to use your service because it's too expensive for you to stop me or them."

I'm not sure it says anything about the other parties involved, but your willingness to knowingly externalize costs onto others says quite a bit about you

It's also almost certainly a bad assumption to make about Google, given that (a) they own the servers (so re-rigging them to just whitelist IPs is entirely possible) and (b) they are a search engine company (so finding the places where they used those servers to swap out the names is entirely possible ;) ).

"Google doesn't provide timeX.google.com as a public service" seems pretty straight forward?

I read that as "It doesn't have the same quality as public Google services".

It links to some lengthy blog post about leap seconds, which ends with:

"Google does not offer an external NTP service that advertises smeared leap seconds."

I only skipped through the blog post, though. Maybe there is a more direct rule regarding the servers somewhere.

Being told "this is not a public service" seems to indicate that it's not supposed to be used by the public. That seems pretty cut and dry.