Thanks for the reply. Try the following on your WM5 i730:
(1) Set the time and date incorrectly in the Clocks & Alarms screen
(2) Run an OTA update (*22899)
(3) This should re-sync time and date

Note that, as you implied, time zone is never altered by the carrier -- the user is responsible for updating this according to his location. However, time zone (at least as displayed in Clocks & Alarms) does not change during DST. It stays set to GMT-X based on your location and does its recalc internally according to registry settings. Therefore, as long as the device syncs to the carrier, the date and time will be correct. This is essentially the case Verizon is making.