As a non-Christian I say all symbology related to 9/11 is fine. If happenstance caused a couple of beams to take the shape of a cross and some people superstitiously found some solace or meaning in it, then the museum should have that piece of steel there.
I you feel threatened our cast out by the symbology that others hold dear then you will never feel part of any society unless you are in the majority group. And that's rather a pathetic world view for anyone. Being in a religious minority that is smaller than atheism in every western country I know what it is to be out of the mainstream but I also don't care that I'm different, actually I like it.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
