"our competitors, who at the time, in our opinion, were kind of exploiting the users"

So, they are fully aware that they're entering an industry where exploiting the users is a common temptation. Like I said, this provides motivation for a slogan referring to that.

"Amit started writing it down all over the building, on whiteboards everywhere."

Imagine literally going around plastering "Don't be evil" all over your colleagues' working spaces: I'm not sure that would be accepted as inoffensive in most work places... IMHO that would normally be a very strong action showing you think your colleagues ought to be reminded.