koldmamadaka – First of all, Yashar Kochacha! May Hashem protect your son from harm and help him to defend his people well! May he give you and your family much nachas!
I am very tired now, but feel that your question should be address. Unfortunately, I am too tired to give a full answer. B”EH I can at least start you in the right direction.
As you and I know, there are a lot of things that we learn in Torah sh’bichtav and Torah sh’baal Peah that are not easy to swallow.
Hashem says, “?? ???????? ?????????”
Hashem’s wisdom is beyond ours and we are required to follow his wisdom, not ours.
Example: According to the Torah ???? ?????? are only punish the Din of Zumamim if they are caught “BEFORE” they succeed. If they manage to get away with it (such as get someone killed) they are not punished ???? ???? ?????.
This defies our logic! We would learn a ?? ?????. If a someone didn’t get away with it he gets ???? ????, then all the more so if he got away with it!!!
But the law is not that way. The law is the way Hashem says it is and we are required to follow it. That is being a committed Jew! Anything less, is being committed to ourselves and our own personal beliefs. That constitutes Avoda Zora.
As far as your question, most poskim learn from the Rambam that people that want to dedicate their lives to learning Torah are exempt from any military service. If this is correct, it is Hashem’s will and we are not allowed to complain, even if it is difficult for us to understand.
This website (YWN) posted a video recently of the Lubavitcher Rebbe, z”l speaking exactly about the points and feelings you expressed. It may help you to watch.
May Mashiach come soon and may the world come to a peaceful state.
(PS. In case you’re wondering, I’m not Lubavitch. 🙂 )