I have also put it after the "repeat until get_shooting() == false" but again to no effect.
Try adding some sleep after that as well.
What turns the LCD on is the camera readjusting it's live view after a shot. Sounds like get_shooting() is turning false a little bit too soon for this purpose for you, at least in the amount of light you tried it in.
Also, the timelapse script probably spends time in a loop checking for time, sleeping, checking for time, sleeping ...
You could add set_backlight(0) inside that loop (I do believe it's safe to call it repeatedly although I can't speak for all cameras out there, if even for mine)