Even if they did let him in what makes anyone think he'd "straighten up?" The Service isn't mommy or a babysitter- the only difference is he'll have the chance to steal automatic weapons instead of Wal-Mart shotguns in the military.
Frankly people like that degrade the quality of our military-I would hate to depend on someone like that in a military situation. The best he can hope for is a years' County, but it sounds like they're tired of his act so he'll probably do two years in the State Pen. As it should be, for his continued criminality.