Have an up-vote. This is the most plausible explanation. They're testing his social skills and how he deals with people who are less technical than he--not testing his technical knowledge.
EDIT: To add to this, I've seen this tactic before on an interview. Interviewer asked me a pretty softball technical question, I nailed it, and then he said, "No, you're wrong, it's [OBVIOUSLY INCORRECT ANSWER]." He was clearly trying to gauge how well I handle someone who thinks they know what they are talking about, but actually do not--which can a surprisingly large number of people in the office.
The most plausible explanation is the guy failed the interview, felt bad about it, then wrote a version of it to make him look good and Google bad to punish them.
I find the thought more plausible that Google had 100s or 1000s of candidates and they weren't willing to interview all of them directly because most are usually crap, so they let some incompetent contractor do a pre-screening.
I really wish our industry could create some generally trusted benchmarks of skill that we could take once and then be done with. As things are, we have to prove basic programming skill with every employer. You'd think this wouldn't be necessary with more than a decade of experience and several degrees in computer science from eminent institutions, but apparently it is. I'm fine with employers asking very particular questions about the domain of work, but we shouldn't have to prove sanity all over again every time.
Really doubt that based on those questions. Recruiters are human and fallible. They form opinions about people, sometimes incorrect, and act on those opinions all the time. This phone screen is the final step before they lose control of the candidate process to the technical team.
Recruiters do reject candidates and create false negative situations when it comes to positions that have a lot of candidates and very few openings. For Google, that would be every position, especially engineering.
EDIT: To add to this, I've seen this tactic before on an interview. Interviewer asked me a pretty softball technical question, I nailed it, and then he said, "No, you're wrong, it's [OBVIOUSLY INCORRECT ANSWER]." He was clearly trying to gauge how well I handle someone who thinks they know what they are talking about, but actually do not--which can a surprisingly large number of people in the office.