His point is that Google's and everyone else's hiring process is subject to large amounts of randomness and capriciousness. Google themselves have at various times mentioned how their hiring scores don't strongly correlate to performance.

Don't feel because you got in that you are some ordained snowflake. If you had interviewed on another day or with another group within Google you very possibly wouldn't have gotten in.

There are many variables at work when it comes to getting hired and hiring.