Sorry I missed this till now... The old way to do soft poweroff, back when it worked, involved editing a configuration file.

But I found that powerlaunch now supports soft-poweroff, even with the new firmware. I must warn you that powerlaunch is a bit hackish at the moment; I've had no stability issues or anything, but it's all configured with config files (no graphical tool or anything), and requires substantial configuration to bring out its full potential.

That said, it does install easily, and the default config works (though it doesn't do a lot). The benefits of powerlaunch include locking the touchscreen and leaving the hardware keys unlocked to control mpd (the music playing daemon), soft power-off, brightening and dimming the backlight from hardware keys (great when you have it turned down and walk out into the sun), and general configurability of what happens after you tap the power key.

And in fact, when powerlaunch does the power-select lock, it doesn't come out of lock when the camera opens, though it still launches VoIP, it can't do anything beyond that.

So it looks like powerlaunch may be your ticket out.