[Avodah] Matzik l'rabim

[Ben Waxman via Avodah]

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