Seems like as long as everything is in the 10.x.x.x/8 range and a user gets there by typing the IP into their address bar, nothing is going to change for you. This is only about mixing public and private contexts. If you have a link to private IP space on a public website, then you're going to get warnings.
I presume DNS names that resolve to 10.x.x.x are also fine to write into your address bar directly?
It seems to me the issue with a DNS split-horizon is that google results return DNS names that are in your local intranet, and thus resolve to a local IP, but you clicked on that link from the outside world, and hence chrome would block that.
I think any sort of split-horizon on devices you don't fully control is going to start giving you a lot of problems going forward. For example, any sort of DNS-over-https is going to make split-horizon non existent unless you control the client device. And presumably if you control the client to change the DNS behaviour, you could turn off this new behaviour too.
Fwiw, I think this is generally good. Network operators shouldn't be able to arbitrarily intercept traffic on their networks.
