This question may be related to a resolved thread.
Apparently, my problem in the linked thread wasn’t fixed by setting DST to No.
I’ve avoided the problem by breaking the time into a separate, hard-coded drop down that is completely unrelated to the actual date/time. There still seems to be no way to have EE ignore DST (and localization) so that if the author posts at 7:00 am, the entry date will always be 7:00 am, regardless of the time of year, DST or the viewer’s time zone.