Ok, with this I was able to reproduce this. Seems like the timezone setting can not be overwritten once it is different than the default value. I was able to reproduce this bug in all our platforms, not only the Tegra.
Officially MS does not support the Remote Admin in CE 7, we ported it from CE6. So MS will not fix this bug probably. If this is a critical thing for you we can schedule a fix for one of our next releases. If you want you can also check the code in \WINCE600\PUBLIC\SERVERS\OAK\SAMPLES\REMOTEADMIN\MODULES\TIMESERVICE\timeservice.cpp if you have PB for CE 6 installed. I think there is a bug in function UpdateTimeZone.