What were the terms of the other 91 cases? You make it sound like the Google engineers were slaving away for two weeks. My impression was that they ran the experiment during that time.
Google doesn't say how long they were working on it or anything at all about the methods they used. Indeed, they don't even seem to be certain how many honeypots they injected.
However hand they issued twenty engineers laptops which is more consistent with an ongoing effort than a single afternoon of Bing and beer - particularly when you consider that if there was a single method applied and it was known beforehand, one engineer could have automated the whole exercise.
The inability to accurately measure honeypot injections is a bit odd. As pure speculation, it may be that they were not sure if the methods they used to get Bing to show honeypots number 8 and 9 were legitimate.