While I agree UA did the right thing, I also believe they are at fault. In the list of published benefits, 1Ks are told they have top-priority and in this case, it wasn't the case. Perhaps the benefit statement needs to be revised to "most of the time".
Personally, if UA was going to trump someone on the list, they should have either put the 1K on another carrier or VDB'ed someone.
Do I think it's worth chasing for compensation, no. But I would shoot an email to 1kvoice.
It sucks, but it would suck more to be going to SYD and have to wait 24 hours. This just comes with traveling.