As long as we are not assuming that the aircraft is in level inverted flight, the diagram would be correct in my opinion. To me, the picture is correctly depicting the descending part of a looping with some substantial "pull" (e.g., following video at 1:06-1:08).
https://www.youtube.com/watch?v=gcfFTZmq7wM#t=1m05
Last edited by aerolearner; 23rd May 2017 at 09:54.
Reason: Link to video