This is right out of the aim guys.
Once the aircraft crosses the white runway line, another aircraft may now cross the threshold if landing or start it's takeoff roll. An aircraft is not going to go into reverse and get back on the runway. Forward momentum will win. Now if aircraft is
approaching the runway and crosses the bars, they are considered on the runway.
Regarding your comment about EGF. You're right, he didn't look, but guess what? What was he doing turning that way...how does he know I want him to go that way? They just switched to my frequency, he doesn't have the picture. No excuses.
Also, looking at the reference in 2-3-5 you are talking about. It talks about general stuff regarding these hold markings. It clearly mentions them in regards to "approaching a runway" in paragraph a. It talks mostly of this "approaching" maneuver later on and then talks about uncontrolled airports.
Generally though right?
Anyways, take a look next time you are out flying and see where some of this exiting traffic is when people are crossing the threshold and departing. Things would be a lot more difficult if we had to wait and make sure the rudder wasn't an inch across the line before issuing the next clearance eh?