Rav Asher Weiss discusses a case in which a small number of graves are found in a place that is not designated to be a beit qevarot. This piece of land is slated for a large construction project, which would in all likelihood mean damaging the graves. He discusses various reasons for moving (or not moving) the graves. One of the ideas that he brings up is "matziq et harabim" (damage to the public). He concludes that this reason wouldn't apply here; the claim "matziq et harabim" can be used to permit moving graves only if the graves cause teumah to kohenim.
Why would forcing kohenim to take a different path (possibly a very small detour) be sufficient reason to move graves but a major building project not?
PS: For a variety of other reasons, RAW permitted moving the graves.
Ben