I don't think that's unique to Google. I've gotten the silent treatment multiple times at other large companies, after being accosted by a recruiter. At Intel, it even happened after I received a job offer.
I was on a project that was in crunch mode, so I asked if I could start in three or four months (instead of three or four weeks, like they wanted). Apparently, that was such an egregious breach of etiquette on my part that the hiring manager (an engineer) stopped responding to phone calls or email. And it wasn't as if my start date came out of nowhere -- I mentioned the issue during my phone interview, during my onsite interview, and on the form they sent me where they wanted me to list my availability.
I was on a project that was in crunch mode, so I asked if I could start in three or four months (instead of three or four weeks, like they wanted). Apparently, that was such an egregious breach of etiquette on my part that the hiring manager (an engineer) stopped responding to phone calls or email. And it wasn't as if my start date came out of nowhere -- I mentioned the issue during my phone interview, during my onsite interview, and on the form they sent me where they wanted me to list my availability.