At Google, there's a culture that if something is broken, call it out so that it can be fixed. At best, you will save thousands of employees hundreds of hours. At worst, you'll learn why it's broken. Many problems are inherent in running a large company, and there is no easy fix for them. But many others have simple solutions that make everyone's lives better.
The way I see it (and this is completely my personal opinion here, not speaking for Google), he and other Xooglers who've written posts like this are being Googley. You don't work for seven years at a company without absorbing some of the culture, and that culture doesn't simply leave when you hand in your badge. Posts like this are not all that different from something you would see on internal Buzz or mailing lists, and I think the spirit of them is not to "bash" Google, but to call out things that Google could improve upon even after the Xoogler has left.