[cool_dude85]

I think you may not be worried about targeted attack here necessarily.

Suppose for example that Amazon wants to know how many people talk about some topic or brand, and wants to sell that information, but they think that the mute switch will get in the way of collecting the data.

All it would take is a relatively small sample - maybe 1/1000 Alexas randomly built in such a way that the mic can't be muted - and they would be able to sell these aggregated statistics with reasonable confidence intervals.

Not that I think this is happening, but it is a possible reason I might not trust a single teardown, and it doesn't require worrying about a targeted attack against me personally.