ROFL! Sadly, a boxer characteristic indeed. From your pictures, however, I could not conceive that he's a full boxer. I think you're looking for opinions?
Your pics aren't large, but it's the head shape that tells that there is another breed than boxer here. He has a tapering head and muzzle - whereas a boxers should be square. From the side, we see that his upper jaw is longer than the lower, and we see that his nose protudes (as the vast majority of breeds' noses do) to a point beyond the jaw. Again, on a boxer it should be the opposite. I would guess him to have a scissor bite also. And lastly, there is no sign at all of the characteristic black mask that should extend from nose to the eyebrows...
In short, no, I do not think this is a boxer (even without seeing the full body shape). It is not the strict length of his muzzle that indicates that, but it's construction. It's possible he's part boxer - so from the genetic standpoint, considering the disorders this breed is prone to is worthwhile.