"The Yor absolutely detest organic life. It is their long-term mission to exterminate all organic life where they find it. There is, however, one other irony -- the Precursors designed the Yor such that they would use as their main energy source the same thing as the Iconians. The Yor "eat" in a sense; they have farming of a sort."
The advantage of the Yor might be that they can settle on sub-standard planets (?).
The disadvantage of the Yor would be that they spend time and resources exterminating organic life where they find it. If they run across a Class M planet "Garden of Eden", they would -- if GalWiki is accurate -- convert every hex to a sterile heap. No life. All the lizards and trees and meerkats would be eliminated one by one. Such methodical eradication of "organic life where they find it" might slow down their colonization. Alternatively, they may opt for sterile worlds to start with, given that they would not have to waste time exterminating all organic life.
Also, the new planet options that gain benevolence, pragmatic, or badness often involve organic life. Such encounters with organic life would result in only one option: exterminate it.