The decision making process is very simple: who does the left NOT want Trump to pick for SoS? Then you pick that person. And that person is Bolton.
I find little on Bolton and the Clinton/Blair bombing of Serbia.
https://en.wikipedia.org/wiki/John_R._Bolton
Looks like Bolton even came out against the creation of Kosovo.
http://www.youtube.com/watch?v=ouQwgLBtFcE
This does not mean I found out that Bolton did not advocate for bombing Serbia/Yugoslavia, I just find little mention of this.
I saw someone mention this in a post, Bolton did not serve Clinton of course.
If he bombed Serbia, that would be a deal breaker.