It sounds like the Owners Corp has decided it’s easier to make individual owners pre-emptively responsible for their decking than it is to pursue them for the cost of repairing common property that they may have damaged. This is one of those cases where we all need to get our heads aroung the concept the the Owners Corp isn’t “them” … it’s “us”. And if you want the Owners Corp to be responsible for your decking, then be prepared to be responsible for everyone else’s.
I don’t think there’s anything particulalry sinister in all this as it puts responsibility for common property that doesn’t have any immediate bearing on the integrity of the building back where it probably belongs.