On the one hand, private academic institutions use their colossal endowments to buy real estate throughout their entire history. The economics of the specific transactions are just as sensitive to bull/bear runs in equity markets as Google is sensitive. But you'd have a hard time looking at a specific building and say, "Oh, they should have spent it on something else," even though we have the privilege of seeing academic real estate on timelines of a hundred years or longer.

On the other hand, if you step away from the economics, you'll have a better idea of why it's a bad sign for the company if they're blowing huge cash on buildings. The best secular reason this is a bad move is that it signals a change in the organization's ego. People build these things under the premise that (1) it's important to have glossy buildings to attract junior talent, and (2) it's important to have glossy buildings to retain senior talent. That's definitely the case with academia too.

But Google ain't Harvard, its brand can turn on a dime, and I can guarantee you that 22 year old compsci grads and 50 year old product management vice presidents who think the glossiness of the building is important are much bigger shitbags than 18 year old college applicants and 70 year old professors who might think so too.