That sounds like a "you" problem, not a "me" problem. If "you" are setting up smart devices where "you" don't have connectivity, "you" should provide the connectivity, not "me". (Note: I don't have a problem with devices piggy backing on/extending their owner's network).
TFA mentions possible issues with FTC and TOS violations with customers' ISPs. But what about overages? Who's liable for those? Is there going to be a metered breakdown of network usage? Will AMZN cover costs of overages due to neighbor usage? What about potential liability issues? Infosec issues?
This just sounds like a too easy setup for a class action lawsuit.