I'm wondering if the Air Force can be sued for negligence by the affected familes.
Almost certainly not. To prove negligence, you have to show a duty to the people affected (a tenuous connection, but a slim possibility) and proximate cause, which isn't happening. Form 4473 specifically asks about domestic violence convictions; if he'd answered question 11(i) honestly, the transaction would have ended there. I've also seen arguments that 11(c) is relevant because he was subject to a general court martial, which can give a penalty greater than one year (as opposed to a special court martial, which cannot), and possibly 11(f): I've read that he escaped from an institution; if you enter voluntarily, you can leave freely, but if you're committed, you can't. That last bit is deep speculation based on questionable interpretation of a notoriously inaccurate media; in any case, 11(i) is clearly applicable, and breaks the chain of proximity for the Air Force.
Adding to what Dave offered, you have to look at our legal system (I no longer refer to it as "justice") as a sewer system. It processes and disposes of human waste and waste byproducts. Well our sewer system is old, decrepit and full of ****. That doesn't mean it's a bad system, but it does need to be cleaned out and repaired.
