But the research is not even published yet
We're only reading a summary of the paper because apparently the authors aren't confident enough in its quality to release it publicly.
You can't claim that Google dismissed this paper out-of-hand while simultaneously saying "oh, but it's too much of a draft to release publicly". Uh, if it was too much of a draft for the public why shouldn't it be too drafty for Google? Are we really pretending that Google has lower standards of quality than the general public?
Google consumes a vast amount of energy: "10.6 terawatt hours in 2018, up from 2.86 terawatt hours in 2011."[1]
If training and retraining models is a significant and inefficient part of google's energy consumption, the point doesn't seem insignificant(edit: The most advanced AI model involve as much as computing and energy any programs ever created [2], btw). I'm biased by the impression Google's actual search results haven't improved very much but I don't think I'm alone in that impression.
[1] https://www.statista.com/statistics/788540/energy-consumptio...
I'm guessing the vast majority of the energy usage is for serving billions of requests for various products, such as search, youtube, maps, gmail, photos, etc.., and the cpu, network, and storage requirements for those requests.
Training and retraining ML models is definitely not on the hot path.