I was told by a coworker, when I was over 50 or so, that they could not fire me because I could turn around and make it about age discrimination at that point. I don't know if my coworker was correct — there is, as was mentioned in the blog post, a weaselly way where they lay off whole teams to avoid the blowback. (And then may cherry-pick a few of the laid-off engineers and make them a quick offer on another team.)
Earlier though in my career I had a very cool manager (hi, Steve!) that made it clear to me that The Corporation doesn't give a fuck about me. That, to that end, I needed to chart my own career path and not rely on might bright-eyed "beamishness" to get me anywhere.
In the end I did stay with Apple for the whole ride but was quicker to switch teams when I thought I was being either overworked or under-compensated. Seeing the company as the cold entity it is was in fact a liberating concept for me. Fortunately I didn't need to be personally impacted by a layoff to find that out.