I don't know how things are in NSW. In the ACT the EC has to approve the proxy and absentee voting forms for a general meeting. The motion would have been on the forms at least as a numbered motion if the EC had met to decide the agenda to be mailed out with the proxy form to all owners. The manager could not then take the motion off. On the other hand, if this is just a motion requiring an ordinary resolution to have the general meeting endorse the EC's decision to remove the shed from common property or require its removal, that motion could be put from the floor of the general meeting (at least in the ACT, I think).