SIA AO is not the same as civil service AO. Civil service AO means they rotate you among different functions in prepeartion for you to move up to general management roles like stat board directors, perm secs or MOS.

SIA AO really means doing administration, i.e. they will rotate you among different departments doing largely administrative matters. Joining as AO means that you will be jack of all trades, i.e. easy to find work outisde. But the downside is no pay premium as there is no special skillset or experience