Re: Come to think of it ...
I took a look at that, using Google Maps and the distance/elevation calculator at daftlogic.com, and I still don't think it flies.
The straight-line distance between the Black Mountain and the Milpitas campus is 23km, which at 29GHz corresponds with about 2.8dB of attenuation due to atmospheric absorption (using the attenuation curve shown in the first reference to the EHF article on Wikipedia - note that the curve shown in the article itself corresponds with a much higher elevation - since this case is much nearer sea level curve A in the book applies).
Anyway, 2.8dB seems great, until you take into account that mm waves severely suffer from rain fading, foliage blocking, scattering etc., each of which are impossible to engineer for and therefore render the link highly unreliable).
The fact that at 10km the Cupertino campus is much closer to the Black Mountain doesn't change my opinion.
All of this in addition to the fact that the subject of mm waves and 5G is about the air interface, not backhaul. The "for backhaul?!" quexclamation in the title is clickbait.