>By what mechanism could Google prevent themselves from ever being able to do this?
The law.
The law.
if you mean, cant stop you considering it, then thats fair, but then the point has no value?
Claiming laws only punish actions taken so they can't be "preventitive" by preventing others from taking those actions is either naive or just plain intellectually dishonest.
I'd really rather not see companies like Google (it any other, for that matter) making laws. Lobbying is bad enough.