Yup that's basically it. The hack was just in getting Tensorflow to accept/load its neural network definition from the JS bundle (what CodePush distributes for you) rather than from the main Cocoa bundle.
Just as a note, people/developers have had messages from Apple telling them that they need to remove code which allows them to update their app outside of the app update/review process.
Really cool stuff! I didn't even realise you've switched jobs, but that explains why I didn't see you when we popped in at Townsend the other day! Keep up the good work.
See https://news.ycombinator.com/item?id=13817557 for some more detail/discussion.
[edit: Apart from in Apple-approved manners]