Reading the Sydney forums, they understandably are not happy. They are hoping this clause helps them out.
12.6 Except in exceptional circumstances, FFA will not approve a player
as a Replacement Player if that Player has played for another Club in
that A-League Season if the Standard Player Contract in respect to the
Player's previous club was terminated after 1 December in that A-League
Season.
[Edit: can't seem to find that in the 08/09 - 12/13 copy of the CBA on the PFA website]