The NSW Act might be worded differently from in the ACT but in the ACT a special resolution requires 1) a majority in favour and 2) “the votes cast against the resolution number not more than 1/4 of the total number of votes that can be cast on the resolution by people present at the meeting (including proxy votes)”. [It can also be done on unit entitlements in a poll vote.]
People abstaining on a particular motion are nonetheless present at the meeting and could have cast a vote. So, if there were 100 people eligible to vote at the meeting, 51 voted in favour, 25 voted against and 24 abstained, the motion would pass as a special resolution. On the first criterion, there are more votes in favour than opposed. On the second criterion, 25 ‘no’ votes out of the 100 “votes that can be cast on the resolution by people present at the meeting” is not more than a quarter, even though it is almost a third of the votes that were cast. Both criteria are satisfied and the special resolution is passed.
I think an abstention is an active decision to neither support nor stand in the way of some proposition, which sounds exactly like what the original poster wants to do.