I would avoid WT policy altogether and use the Bible. Probably won't work but...
Read Acts 10:1-8 and 21-48.
Cornelius was a Roman general. He was in ACTIVE military service. Were his prayers unacceptable to God because of his duties in the military? No. God's own angel said (vs4) , "Your prayers and gifts to the poor have come up as a memorial offering before God."
On this same day, while being active in the military in vs 47,48 he was baptized. There is absolutely NO talk about him leaving his military duties at that time. He may have had problems with it later on as persecution towards Christians increased (we don't know). But there were no requirements of him leaving at the time of his baptism. Also note that he did not have to go through questions with 3 elders to be "approved" by them to be baptized.
So regardless of what WT policy is, this shows that one can be acceptable to God while serving in public service. The WT twists the meaning of the scriptures regarding "Being no part of the world". This does not mean being involved in helping or defending others. This largely has to do with attitude towards things of the world. Watch any reality show to see how the world acts. My wife is addicted to them.