I can indeed legitimately impose my suspicions, because behavior of people with power in organizations does not exist in a vacuum and instead tends to follow certain lines based on human behavioral impulses, cultural factors, etc. Of course there are exceptions, but not preparing for fallout from not doing an optional but encouraged thing at work is sort of like showing up at work in your underwear because your new company might be a pants-optional company even though most companies aren't.

In this case, if I were a Google employee looking to advance in the company, I would show up on the suggested days with a convincing-looking smile on my face. If I was already at a level where I didn't expect to advance further without changing companies, I would continue working from home and be prepared to be on the top of the list the next time layoffs came up.

I don't disagree with any of what you say but seeing the devil everywhere has drawbacks too, starting with possibly being plain wrong. In this specific case the policy came precisely because employees asked for it..

Also to speak your language, one of the reasons people propose WFH or other benefits is precisely because they feel they don't hold so much power in a market where SWE are in high demand. So they 'sort-of-expect' you to use the benefits as proof that you 'sort-of-value' them and will stay. That doesn't mean you won't have to s** d** to advance.