The thing is, these are YOUR gedolim. The people who think frum Jews should be in the army certainly hold these gedolim to be gedolim and hold them in reverence and respect, but they may not necessarily hold by their psak in this matter. It’s the same way that you may hold a chassidishe rebbe in high esteem, you won’t necessarily follow his rulings. They have other rabbanim whose psak they follow in this matter.
The whole “your gadol < my gadol” thing is irrelevant- “the gedolim” may all be great, but if these people happen not to follow their psak in this matter, you’re working in different spheres.