Someone having a religious object on or near their desk does not seem like a big deal and perhaps to the people around this person it is not. However, it can seem intimidating to someone else, especially someone who is an underling of this person and feels there must be agreement with the employee's religious faith.
The use of definitions becomes a very limited scope. The ACLU makes a list of "offensive" or "inappropriate" objects based on their own agenda. Other offices simply state no religious artifices at all, and then only enforce that when there is a problem. The right way to approach this is much like sexual harassment. Create a loose definition about what insults who, have the first mechanism in the system be someone asking someone else to stop an activity, and equally escalate if the situation progresses. Imagine what would happen if someone just asked "hey, could you move your cross to somewhere that wasn't in view of everyone?" Imagine if the response was just as simple. It never is, because oppression can often come disguised as the exercise of the majority's "liberty."
According to the first amendment of this countries constitution, we have the right to follow any religion that we may have faith in, and no one can say anything about it. An employer should be able to have any religous object that they want, and they can decide if it hurts business.
I do not think that the US government needs to adopt any type of objects and definitions from another organization or Union because we have a right to our religion and sounds like it would cause more harm than good. People should be allowed to have their religion during the workplace.
I personally think that the American Civil Liberties Union would be a lot for the U.S. government to take on the reason being is because of the inappropriate religious objects in the workplace. I personally think that the American Civil Liberties Union and the U.S. government would be more of society.