The word "establishment" has been tortured beyond all recognition.
The idea that the simple presence of a religious symbol somehow "establishes" that religion is inane. The Founding Fathers knew damn well what a government establishing a religion meant, and why it was something to be avoided, and they weren't talking about paying the gardening fees for crosses in a park.
Do we go through government-financed public museums and remove all the art related to religion? Why or why not?
You can make a case that a cross on a hilltop might oppress people whose mind works that way, since it's hard not to see it. What about the near-microscopic cross on that city seal?
How far do these people go before they finally qualify as nuts?