yankel,
I am not deciding anything here, just trying to understand the issue. entitlement attitude does not start & end with a specific issue of draft. Before going to exemptions, let’s start from the beginning – what are person’s position & obligation towards a community and a country. If you agree that you part of the community, then certain obligation might apply or not. Say, Bava Basra says town dwellers need to contribute to protection. T’Ch do not need protection and thus only contribute to upkeep and not security.
One major question here is who is a T’Ch here. As you mention above, you are thinking of a vulnerable 18-y.o. with 4 years of yeshiva. We are bnot talking about exempting Roshe Yeshivos.
There is YD 243:2, for example. What does it say?
There are many mailos of a T’Ch not all of them strictly halachik,. Here is a couple that might be halachik:
If you see a T’Ch doing aveira in the evening (sic!), do not reprimand him in the morning as he surely did teshuva. So, anyone who did not do teshuva for an aveira for a day is not T’Ch?
Just came up in B’M daf: you can give T’Ch his lost object without simanim if he is only known to change his words re: learning, bed, having good dinners. So, anyone who said something crooked unjustified is not a T’Ch for this halakha….
All of that does not mean that there are no good reasons to keep 18-yo away from non-religious army. But if you appreciate that you have an obligation and looking to justify avoiding spiritual dangers, then start actively working on alternatives that could at least partially compensate. Organize fully chareidi units; help with training; work in cyber security; take jobs from people who are deployed (major limitation of Israeli army is that most large operations have to be quick to return people to work, can’t afford a standing army …); work more than others to pay for the things that even Talmidei Chachamim are supposed to pay – roads, water, electricity … If you don’t, that is what I call “entitlement attitude”.