Is there another section in the SSM Act that speaks to this?
Not really. There are issues of personal privacy and security that would mitigate against any by-law or strata law requiring keys to be left with third parties. Having lived in a building where a corrupt building manager allowed security mates to enter apartments using special master keys I can see why there is no requirement for owners to leave keys with anyone else. This is the relevant section of the Act.
122 Power of owners corporation to enter property in order to carry out work
(1)An owners corporation for a strata scheme may, by its agents, employees or
contractors, enter on any part of the parcel of the scheme for the purpose of carrying
out the following work:
(a) work required or authorised to be carried out by the owners corporation in
accordance with this Act (including work relating to window safety devices
and rectification work carried out under Part 11),
(b) work required to be carried out by the owners corporation by a notice given to
it by a public authority,
(c) work required or authorised to be carried out by the owners corporation by an
order under this Act.
(2) An owners corporation for a strata scheme may, by its agents, employees or
contractors, enter on any part of the parcel for the purpose of determining whether
any work is required to be carried out by the owners corporation in accordance with
this Act.
(3) In an emergency, the owners corporation may enter any part of the parcel for those
purposes at any time.
(4) In a case that is not an emergency, the owners corporation may enter any part of the
parcel for those purposes with the consent of any occupier of that part of the parcel
or, if the occupier does not consent, in accordance with an order of the Tribunal under
this Division.
(5) A person must not obstruct or hinder an owners corporation in the exercise of its
functions under this section.
Maximum penalty: 5 penalty units.
(6) An owners corporation is liable for any damage to a lot or any of its contents caused
by or arising out of the carrying out of any work, or the exercise of a power of entry,
referred to in this section unless the damage arose because the owners corporation
was obstructed or hindered.