Ultimately this is a win-win for TSA in that we are going to be screening a subset of passengers at another location, thereby removing those individuals from a checkpoint line at a larger airport.
We suspect that he left the checkpoint under the impression that his screening was complete. The fact that the machine alarmed should not be a cause for concern, as some commonly found substances can set it off.
We suspect that he did not realize the screening process was not complete, but nonetheless we need to locate him.
The lesson learned here is that passengers need to pay close attention during the screening process.