Likely they had to check the barrier and it was a Safety caution. They did do some work on the wall while the cars were under caution.
We used to have a caution at Flemington to put the blocks back in place - even if a car tagged them and kept going....if that helps someone reconcile a local track example. Why? For safety reasons. Same drill, different day.
Walk a mile in the shoes of race control and give them the benefit of the doubt - or keep on bashing away with whatever comes to mind, whatever suits one's fancy I guess.