Why should the 757 have been descended instead of the 154? If the controller wanted the 154 at the lower level so be it. Rules of the air are rather academic in this environment, fine in VMC. The stress and workload that the ATC guy were under are not exactly unknown, listen to the density of rt in the London zone for instance, sometimes impossible to get a call in for minutes. Reporting a TCAS advisory is not exactly top priority when you are manouvering the aircraft and looking for the conflict. in any case the situation is now out of the controllers hands and happens very quickly, he certainly doesn't have time to coordinate things. An incident of this sort obviously concentrates attention on these particular circumstances but near misses aren't exactly rare and the reason most do not end in disaster is because, in the final analysis, the pilots correctly following the TCAS commands prevent this. Thus the shortcomings that caused them are hidden. The 154 crew may have been confused, the 'spare' FO though seemed to understand the importance of following the TCAS, pity he wasn't PF.