If people who have issue with military are given someone else to do, you can't simultaneously claim they have to be willing to die.
Without committing to any position on the book itself (it's certainly an interesting Rorschach test), it is at least clearly stated that there are more than enough dangerous jobs available for non-combatant service to still involve risk of death. In the book this is presented as a mathematical balancing: power over the lives of others is granted only after demonstrating willingness to risk your life for others. You can find plenty of fault with that principle, but the book is at least pretty consistent on requiring it.