Really? Because that sounds very much like something they'd do in Iran or Saudi Arabia. Whereas I remember reading somewhere (I forget where) that Thou shalt not make unto thee any graven image. Which I presume includes a monument to the decalogue.
I think the monument was testament of the stone tablet given Moses by G_D, not a graven image to be worshipped, but to be G_D’s commandments to the Jewish people and honors the Judeo-Christian principles this country was founded on.
Whether the nut wanted to make a religious, political, or both kind of statement is unclear.
Graven images would include a printed book, not just a printed monument. Is the Bible a graven image? The problem with taking all things literal is that sooner or later you step in your literal.