Actutually this is explicitly forbidden for the case that a user is printing from sd card. As we don't see this we do not want to disable temperature and power of in that case.
Starting with next release 1.2.0 you can write real gcode script. I took this as a test and write a test for it. So once 1.2.0 is out add this scrip into "Run on Connect" event dependent script and it will disable temperature when idle for 10 minutes and extruder is hot. It only tests first extrude rbut you can easily modify it for more extruders to test.
; Check temperature every 60 seconds and disable if extruder is hot for 10 minutes
@func temperatureCheck
@echo Temp Set {{ext_0.temp_set}} act {{ext_0.temp}}
@set global.hotCount {{get('global','hotCount',0)}}
@if {{not(job.running) && (ext_0.temp_set > 30 || bed_0.temp_set > 30)}}
@set global.hotCount {{global.hotCount + 1}}
@else
@set global.hotCount 0
@endif
@if {{global.hotCount > 10}}
@echo Reset temp {{global.hotCount}}
M104 T0 S0
M104 T1 S0
M140 S0
@endif
@timedCall tempertureCheckTimer 60000 temperatureCheck
@endfunc
@timedCall tempertureCheckTimer 60000 temperatureCheck