Just reading this quickly, it looks weird to rename a .._get_.. into handle_delete
I think I saw somewhere that WSF_METHOD_HELPER is by default for GET and HEAD .. and for other we have this kind of WSF_DELETE_HELPER

would it make sense to have a WSF_GET_HELPER 

and a deferred  handle_method   instead of send_get_response  in WSF_METHOD_HELPER  (and this class would be deferred)