In the above situation, I would say it is alright. It really comes down to the operator.
I would make sure the glow plugs are not operating (disable the glow plug relay) and use a small shot of ether. I would also only use it for short term purposes as it really isnt the greatest for an engine.
That said, I will always have a can in my truck. That way if we have an artic blast down here in Tejas and its 50 below zero I wont have to bother with running the batteries down with glow plugs. Crank it over, and have someone shoot it with ether. (Yes this scenario wont ever happen