Google contains multitudes. I don't doubt that your personal experience was the opposite end of the spectrum from mine.
I maintain that firing is an extreme resolution here (taking the claims at face value of course). Surely this employee has demonstrated the capacity to deliver impact and could be redirected if properly incentivized.
As a Xoogler you should know that the "impact" they want is, making leadership look good, what you shipped or even whether or not you shipped is nigh irrelevant.
This did the opposite, didn’t it?