I'm not quite sure what the statue has to do with historical preservation, though. I mean, unless that statue is placed in a location that is historically relevant. For example, my city will often put up different works of art in the downtown area, and then move them after a year or so and cycle in new stuff. Why are these statues untouchable? They aren't melting them down or anything crazy like that, they are placing them in an educational setting, it seems.
Basically I agree with you that the reason is suspect for these statues to be moved (the PC angle) but I question whether they need to be there for historical preservation.