I feel for the family, and I understand their wish to hold someone accountable. AA as an entity isn't in a position to keep all its members safe--from each other or from anyone else. Ultimately, individuals are responsible for their own safety. I've known a few groups that, once they became aware of a member's repeated transgressions with female newcomers, did ban him from their meetings (after a group conscience). But banning people because of their history would keep a lot of people out whom AA is there to help.
Criminals too dangerous to be around others should be locked up for as long as possible. But the law has its limits in what it can do, and so does AA. And eliminating court-ordered treatment (AA or an alternative program) still would not prevent people who are predatory from coming on their own.
This situation strikes me as simply a risk of living in a free society. People can be made "safer" by imposing all kinds of restrictions on activities and associations, but then we are not living in a free society. We have restrictions on what the law can require of people for the common good. It's in the Constitution.
I think meetings can be made safer by encouraging members to speak up when they do become aware of predatory behavior, and some kind of action being taken to prevent predators from opportunistically preying on more vulnerable members. But every incident cannot be avoided.
There's plenty of information out there about potential dangers of predators. It's worthwhile to keep informed and to take action to protect yourself and others you notice at risk of victimization.