NC 1701,
By asserting that the big issue is taking off from a non-operational runway, not making the wrong turn, it seems to me you're treading on really dangerous ground. I don't see how you can separate the two actions and deem one to be more serious than the other. The wrong turn brought SQ006 onto a runway that, for their purposes, was CLOSED PERIOD but not easily recognizable as such (that it might have been officially only partially closed is immaterial). You're in effect saying to a pilot, don't worry about taking a wrong turn during taxi, if you wind up in the wrong place you'll be able to sort things out.
It seems to me that maintaining situational awareness AT ALL TIMES is, for an airman, paramount.