There is no such thing as an insignificant "quick blog post" when you are the CEO of a $365B company.
And it is unlikely that the goal of the post was to solicit ideas given that it didn't solicit any ideas.
And it is unlikely that the goal of the post was to solicit ideas given that it didn't solicit any ideas.
And I don't agree, one of the company's stated purposes is "incubating urban technologies". They aren't actively asking for any idea out there, but they clearly intend to interact with other startups and inventors at some point, and the only way to make that happen is to get your name out there.
And again, what is the downside? If there isn't any, then "because we wanted to" is a good enough reason.
They have not announced a product yet, only a research area.