The fundamental problem is that what you want to do - leave a bag somewhere and depart without having it associated with you - is exactly what a bomber would want to do. Therefore, I do not believe there is any way to do this without risking being mistaken for a bomber. A baggage belt would be a particularly good target for a bomber since there are lots of people crowding around, and you can get stuff there without going through security, so I would not expect that to be a less conspicuous place for your scheme.
I think that trying to leave a bag at an airport will inherently cause a security scare. If you are stopped at the scene, it will be unpleasant. Hong Kong airport police carry submachine guns.. If not, even if it is found out that your bag was harmless, you may be suspected of intentionally leaving your bag to cause a panic. Given the heavy surveillance normally found at airports, it is quite likely they will be able to identify you, and you may face legal trouble.
I would strongly advise against doing anything of the sort. Suck it up, take the bag away with you, and dispose of it in a less sensitive place, far away from the airport.