Google has nothing to do with it. Nest is a subsidiary of Alphabet, and even then the responsibility is 100% with Nest and not Alphabet. Tony Fadell comes from an Apple pedigree, if we're blaming one of the two.
The name change to Alphabet and movement of project/product ownership to Alphabet's subsidiaries is a recent thing. People will, for quite some time, equate Alphabet and Google when speaking about the parent company (Alphabet) in relation to other subsidiaries.
How can Alphabet not have any responsibility if they're the ultimate owners?