It is very good idea, and a nice way how to integrate with existing libraries.
It shields user from one round of conflict resolution handling.
I have created a small diagram to better understand that and it revealed one more fact:
As seen on the diagram, user would still have to Merge on the programmatic layer, where we could offer a DiffMatchPatch alghoritm,
and/or integration with selected existing libraries (e.g. AngularJS ResoureProvider or Restangular or similar Ember approach).
I believe we don't have to handle "I work for second and later requests" problem you mentioned in the blog, since I assume ServiceWorker will react on the REST calls from the application once it is registered (not sure that's the case). That's with a question mark. :-)