In some cases, handling agents have an agreement with airlines where flights on schedule get priority over delayed flights. I have never actually come across a scenario where they've ditched a delayed inbound half way through to go and deal with an on time arrival, although I guess this could be one of the clauses in the contract if there were no loaders available to deal with the other flight. One thing that does confuse me slightly about this though is that TCX baggage is done by Menzies and they don't deal with any T2 based airlines.