‘Golden rule of accumulation’ refers to the savings rate that :

The printed option says maximises the growing per-capita consumption; it does not say maximises its growth rate. Golden-rule accumulation selects the savings/capital level giving the highest sustainable consumption path. With labour-augmenting progress that per-person path can grow, while consumption per effective worker is maximised. Thus this choice states the consumption objective; output-growth maximisation and unspecified investment optimisation do not. The earlier hold misread the adjective as a growth-rate maximand.