Earlier quoted context omitted.
If they do then why don't they share it? I mean they must realise this is a pretty unpopular decision so why not share their justification. Otherwise it's just an appeal to authority - "Ours not to reason why.."
I don't know, but I think it's reasonable to assume that their primary concern is productivity, and that at a company like Google, that concern will be analyzed in a data driven way. Perhaps they don't want to insult their developers by implying their productivity dipped, or something.
A lot of politics gets much harder in remote work, and this is what these people are best at.
It's not productivity, it's politics that is much harder to do when remote working.