Of course it's always been understood as poor form to personally attack another employee, there was never any need for a rule saying so. In the same way, a "culture of openness" is always embraced with the implicit caveat that being "open" about criticism of decisions made by executives is also unacceptable and will be met with retaliation. That doesn't go both ways -- executives can be openly critical of you by name and on whatever terms they wish. Our generation didn't invent office politics, after all.

So this new rule is so broad as to be meaningless, it's sort of like making a new "no complaining" rule (which isn't as uncommon as you'd think). It demonstrates that the "chafe" was never about the rule. When we see workers purposefully making these criticisms anyway, as with this new hire or someone like James Damore, it means they've probably already understood that google won't act unless it represents a serious threat to their productivity. This is the company's first initial attempt to squash that sort of effort.