I think that statement refers to early IPv6 allocations from the old /23 blocks. Before APNIC received the /12 allocation from IANA, we use sequence allocation
method to make /32 allocations and reserved up to /29 for every allocation. That was the practice for all RIRs in the early stage. I believe this policy proposal is trying to address those reserved space.
APNIC has been using spare allocation method to make IPv6 allocations from the /12 block since we received it from IANA. We don’t do reservation in sparse allocation,
but in fact every allocation has a room to grow. Current /32 allocations from the /12 block can grow up to /24 at this stage.