On the other hand, if you're organizing a walkout, you're probably pretty fed up already. How far are you from quitting at that point? Probably not very. If you organize the walkout and nothing changes, even if there is zero retaliation, do you quit?
At a minimum, this probably indicates that there was not enough improvement, fast enough, at Google.
Note well: I am not saying that there was not retaliation. I am saying that this, by itself, does not prove retaliation.
How dissatisfied? I'd guess pretty bad. Dissatisfied to the point that you're willing to do something that has some possibility of costing you your job. So they want to stay, and yet they're not that far from being fed up enough to leave. (Or so it seems to me, someone who is not at all in that situation...)
I guess my biggest surprise was that there wasn't a second, more severe "walkout" or "strike" after Google declined to respond adequately. The Walkout made news but it wasn't nearly a strong enough action to really say it was all they could do. Most of the people who walked out went right back to their desks after work and kept working.