Killing People Shouldn't Give You Special Rights

Wisconsin has joined Illinois and Texas in allowing veterans to receive free tuition at state universities and technical colleges (scroll down to the bottom). Citizens who don't volunteer to kill people in other countries will have to pay higher tuition to cover the expense. I'm no constitutional expert, but this seems unconstitutional in that the state is discriminating against people based on their occupation and viewpoint. For every veteran getting free tuition, there will be a pacifist forced to pay higher tuition. How does this differ from saying anyone who is a Christian can get free tuition? Or anyone who is registered to vote gets reduced tuition? (which would discriminate against people who are morally opposed to participating in politics.) I would love for an anti-war group to challenge this policy.