When any artwork is commissioned as a part of a structure, it does not get any special treatment if the structure is modified or removed. If it was a set of paintings it would be easy to move them to another location for viewing, but in the case of a mural on a public building, it is not art as much as it is decoration. So if the decor changes, so does the artwork. C'est la vie.
I don't think it is a question of offensive or not. If it is practical to remodel the structure, then the changes could necessitate the removal of the mural no matter what the content. Some people however will use the content as a political tool to make a statement regardless.
Lou