I'll go with Occam's Razor: Amazon just responded to Google's newly announced pricing. To believe they guessed correctly or they have a "mole" is pretty far fetched.
So your version of Occam's Razor is "Amazon hurriedly cut prices on a profitable service without much time for evaluation" over "someone at Amazon told Google about upcoming price changes while Google had time to decide they could jump in early on it".
I'm not saying that either interpretation is wrong, but I think your use of Occam's Razor here says more about your assumptions than the nature of things.
Could it be that Amazon had a less significant price drop planned, Google announced theirs and Amazon decided to increase their drop to match? Amazon would have already evaluated what they could drop to, so they'd know as soon as Google announced they could match.
I'm really just responding to the idea that "a mole" is farfetched. There's a reason that Apple is known for being incredibly paranoid about people leaking business secrets: it happens, often.
So in this explanation, Amazon does not proactively investigate how much they can cut prices while remaining profitable? That doesn't make much sense, does it? It would make sense that Amazon knows exactly how much they can cut prices so that they can immediately respond to price cuts from competitors in their highly competitive market.
