This head position is completely natural.
For a playful and energic horse.
For 0,1 seconds.
Not for 10 minutes driven by force.
Not until the tongue is blue.
Not until the eyes is rolling.
Not until the back loses its ability to move properly.
Not until the horse gives up.
This is also a great example on why we must be very careful when we base our opinions on a single photo. Please research before critizing and keep the debate constructive.