well thats weird, cause I tried to copy what you have there, just left auto-connect off, only the 2 marlins selected, I still have no G lines, I tried saving the machine gcode thinking perhaps the post processor has not run yet, same deal. Turned off debug mode, tried everything I can think of..
hmm, any more ideas ?
edit: question, when does the post processor run, I cannot seem to get the output to change in that window no matter what mode I select, tried closing and reopening the machine control window etc, tried saving multiple times, tried nano/mega, laser mode on/off, if I turn GRBL mode on (first option) I cannot turn it off, like it stays ticked until I close and reopen machine control screen.
edit2: hang on, I look at the saved data and it is in fact M106 S0 etc, the display on the machine control screen however does not show this and still has no G line starts.
edit3: ok I assume you are saving and then reloading the gcode.
edit4: results are inconsistent, if I close and reopen the program leaving it setup with the 2 marlins selected then it works fine, just selecting them if they were not selected is not enough to get the post processor running though. Might be something to look at if you get bored, apart from that I can work with it

will recompile my arduino source to use a D10 fan and see how it goes. Looks good though, still not sure how I will get the plasma to punch through at the start yet. Will have another look at what marlin can offer I think.