Strata Manager shouldn’t be making these decisions. He works for the owners and they have the final say. SM can advise owners of the law regarding issues (assuming he knows which it appears he doesn’t).
I’m assuming cost is above the OC limit so all owners have to vote on issue. If cost is within OC limit OC can decide the issue.
Surely their is some mechanism to vote on issues outside of the AGM (in QLD we hold Flying motions that are postal vote or email votes by committee or all owners).
Agree with other posters this is BC cost NOT yours.