I'm not sure that I buy the 'liability' line.
As usual JWs think that they are unique in everything they do but in reality they are not. Lots of churches have housegroups. And surprise, surprise, they think that they are very important because they are where friendships and relationships are made. Of course they aren't regulated like the JW version was and they are exactly the places where things are discussed properly and objections raised etc.
But I have never heard of a church having any concerns about liability. Never. And these are churches who do carry out proper checks on their people and do adhere to health and safety regulations. But I've not heard of any worries about liability.