A ToS is a contract between a service provider and a user, Google doesn't need to agree to that contract to use its own services, I don't even know if it makes any sense legally. Of course ethically one would like the same rules to apply to everyone.
Is a violation with the Play Store ToS really necessary for Google to be allowed to throw you out? Last year, they did a witchhunt on third-party YouTube-apps capable of background playback on the basis of those supposedly violating the YouTube ToS, not the Play Store ToS.
the play store developer agreement says your app can't violate anybody else's ToS. A violation of the youtube ToS is an implicit violation of the Play Store ToS. Violating Facebook or Twitter's terms will get you kicked off the play store too.
"4.4 Prohibited Actions. You agree that you will not engage in any activity with Google Play, including the development or distribution of Products, that interferes with, disrupts, damages, or accesses in an unauthorized manner the devices, servers, networks, or other properties or services of any third party including, but not limited to, Android users, Google or any mobile network operator."