Its easy to be a consciencious objector when you have others protecting your butt...
I don't have any issue with people that don't want to serve in the military because they can't kill anyone, for whatever reason, that doesn't keep yopu from serving in the military (if you have to) as a medic or support person.
In regards to Blood, yes, it shoudl be 100% up to the individual, especially since the biblical passage(s) have nothing to do with savinglives or medical procedures.
One question though:
How dangerous and how much complications are there with blood tranfusions?
A medic friend of mine told me the the dangers are in emergency medical transfussions with "universal" blood as opposed to when your correct blood type is available and ready for you.