Hi Chris,
Costello and Tullis have an interesting interpretation to the observations relating free-oscillations to earthquake occurrence and triggering. But it is an interpretation which which is unique to this one instance and cannot be generalized to all such occurrences.
Studies by several other researchers have also shown periodicities in earthquake occurrence at free-oscillation periods, so I would not dismiss the entire subject out of hand on the basis of this one interpretation. In other words be careful not to throw the baby out with the bath water, where there is smoke - and there seems to be some visible here, there is often fire.