... no one but the present author will see this photo as somehow related to the crusades, and certainly no radical Muslims will react in such a way (especially in view of the clarifying comments in the post, that compare the photo to Iwo Jima) (link).
Ok, enough sarcasm.
Maybe the symbol of the cross offends some Muslims, but it is not principally the symbol of the cross, but the reality of the cross that offends them.
Islam denies that Christ was God, and that Christ died on the cross.
The idea that a person of the godhead could suffer and die is unimaginable to the Koranic mindset: it is offensive.
But a building ornament: that's trivial, even if it is superstitiously venerated by Christians.