I submit the connections at Google are unbelievable. It seems reasonable that you could in fact learn substantially faster in that environment. I don't know if you can cram 6-7 years into one, but maybe in 2-3.
A PhD isn't so much about learning the material as it is about learning to manage and complete projects. Your job is to identify unsolved problems, come up with ideas to solve them, and carry it through to a few completed research projects. Depending on your field, a lot of this can become more managing logistics and people than "pure" research.
In my experience (which, admittedly, has only involved much less flexible corporations than Google), you don't get to the level of responsibility you have as a PhD student or postdoc until you've been with a large corporation for >20 years.
I admit I have a slightly skewed view, but I've very skeptical that this is anywhere close to a complete PhD program.
It looks a lot more like a 1-year internship on an R&D team. Still a very good and useful thing, but you're not the one responsible for completion of projects.
I think what they really meant was that this program would be similar to (one year of) a top masters or Ph.D program, which would be plausible. Your inference of 2x doesn't meet the giggle test.
It's going to vary person to person of course, but I'd expect the learning rate to be at best about the same as a top program.
