I have discussed this with CASA FOIs on several occasions, usually during our inspections. The Ops manual is worded to allow solo hot refuelling when the circumstances require, mostly on bushfire bucketing ops when the fuel load is light (30 mins useable) and you can't stay away from the action too long. CASA has always agreed to it.
As i recall it, (I don't work there any more) the conditions were:
Skids
Frictions
Idle
Stay in the immediate vicinity.
Use your brain.
Obviously there was no condition to allow somebody to have lunch under a tree for 45 minutes with the engine churning away - obviously being paid for the Hobbs meter.