It is quite disturbing that Amazon has the ABILITY to satisfy this request
What purpose is served by keeping data Alexa hears longer than a minute? If they want to use it for other purposes like training speech recognition, it should be anonymized and filed away.
If law enforcement files a request, Amazon should be able to tell them "sorry, that data is wiped almost immediately after Alexa hears it, we don't have anything to give you". Sure, if he said "Alexa, order 10 gallons of bleach, one day delivery" or "Alexa, how do you remove blood soaked into the wood underlayment beneath carpet" there may be a textual record of those transactions (though I'd argue no consumer friendly purpose is served by keeping records of the latter, either)
Obviously he knows he didn't make any such requests, and to the extent it may have recorded ambient noise I guess he knows where Alexa is located versus whatever would have been overheard if a crime was committed, otherwise he wouldn't have approved the release.
The 140 gallons of water usage is a bit damning, but entirely circumstantial. The problem he has is that if they can prove their timeline then his story about filling the hot tub comes undone. He better have said something like "the only thing I can think of where I would have used that much water was filling my hot tub, but that was 12 hours earlier" so the prosecution can't claim to the jury he lied to the police about the water usage. I suspect that will be what gets him, not Alexa.