To be sure you need a nod from Sparky or Scooby but It's almost certainly ok.
Just before I clicked the photo I said to myself that it's probably a small rifle like an Ultra ... which it is.
I can see that stance being used in the military for short stubby combat rifles like bullpups etc. The Ultra is so short and light it also lends itself to that position. Don't the military guys carry the guns folded across their bodies? So maybe they are trained that this is the fastest way to get the rifle up and into position when they come across an enemy??
It's what people get used to and find the best for them.
I've just tried it with a S200 and it's not too bad ... I then tried it with 12 pounds of 77 in a target stock and I fell over and banged my nose on the floor.