What he posted was on an internal message board specifically for employees to discuss controversial subjects. It was only public because another google employee got upset and made it public.
Again, I can't help but think what you people really want is the inalienable right, not to "free speech", but to be Offensive Without Consequence. And again, Damore is a genuine celebrity now, he's a very bad example of the kind of repressive woke hegemony you're invoking.