I think their issue is more about the money hat yeshiva guys get from he government without having served in the military. Some want to tie that stipend to military service.
There are other things chareidim could do besides serving in the military. They can do Sherut Leumi instead. I believe serving in Magen David Adom qualifies for that – let more chareidim work in MDA, and they can continue to get the stipend. There are plenty of other opportunities in Sherut Leumi that would be acceptable for Chareidim.