This is a good learning experience for all of us on how discrimination works. Here is the catechism for the day.
Let's start at the beginning: Why was only a cross put up in the first place?
Because the majority did not even think about the other religions in America . . .no one thought: gee, i think that we should make this an ecumenical site for all Americans.
That's the way discrimination works: the majority isn't even aware of other's religions or non-religions. they assume that they should express their feelings in a public place, end of story.
So lessons learned:
a. devaluing minorities is an unacknowledged assumption in most social discourse.
b. the importance of diversity in widening the discourse.
Now that I've cleared that up, next question:
What should we do about it?
Don't remove the cross at this point. Include any others who want to honor the dead according to their beliefs. Including atheists.