Codswallop!
CRM means what exactly? Informing ATC of a bomb threat is nothing to do with it.
And as for SOP's, well bomb threat actions are not in any carrier's SOP manuals (can be located in QRH or equivalent and detail nothing concerning ATC communication). A lot of other on-board actions need performing, which take time and effort for both FD and CC, along with flying the aircraft and preparing for approach and subsequent overweight landing.
Communicating with excitable ATC can bring about a dramatic increase in unnecessary workload, as I've experienced when issuing PAN calls in Southern Europe. Best stay quiet and concentrate on the priority tasks.
Once landed, and before taxi-ing onto stand, a call to ATC would then have been in order, I reckon. As for ground preparations prior to landing, emergency services would do nothing extra in such a case; they are on full standby for an accident at any given moment. Well at some airports anyway....
Finally, bombs are usually activated by pressure devices or timers, and are intended to go off in flight.
Some of the previous comments are evidently from non-pro pilots, as per usual.