Could have been a previous beta version, but I'm not sure. It's still a bit unclear to me how the defaults are taken and how they're controlled. But mainly it seems that, for example, whatever you have last set in the Clock application will become the default. For example if you change the sound for one Alarm, then that will become the new default.
qdbus --system com.nokia.time /com/nokia/time com.nokia.time.set_default_snooze 600
Didn't notice it earlier, but the enabled works for disabling only if something is set in sound (or after snooze apparently). So it seems the clock application is picky that all attributes must be set. I guess I might do another beta update.
The snooze attribute is set (or should be) but unfortunately it seems the clock application does not really show the value, even if it's one of the predefined ones that can be set