This could be implemented two ways:
At a front end level: then the front end needs your posting key/posting authority which is meh in terms of security. And this is what's happening these days with auto claimer tools here an there.
At the blockchain level, it could be done but it's extra complexity and I don't feel like it's worth that complexity. (need to add a field to an account and a new operation to activate/deactivate auto-claiming, plus handle both flows.)