Don’t you think people should ask their LOR before assuming something is automatically muttar.
Within reason, of course.
With regard to the subject at hand (going into the army), yes, one should ask their LOR before joining the army. I never implied otherwise. (My objection was to the absolute categorization of it being forbidden — that does not mean that it’s automatically permitted.)
With regard to the broader issue you bring up, that only applies if one believes there might be grounds for something to be assur. When I made a chocolate cake for the first time, I didn’t go to ask my rav if it was mattur. When I first began keeping a journal, I didn’t ask my rav if it was muttar. When I first became a ba’al kriah, I didn’t ask my rav if it was muttar. And so on.
On the other hand, when you encounter areas where there are greater shades of gray, then, by all means, one should ask a LOR.
The Wolf