The guys in the photographs had just been in a violent, terrifying fight to the death at night with a fearless and determined enemy and had eventually won. They are pumped up with adrenaline, elation and relief at still being alive. A smile and a thumbs up are entirely understandable and not in the slightest reprehensible. They should not be disciplined.
The crime, if there is one, lies with the photographer who recorded the event and subsequently sold the pictures to the media sharks to exploit. He and the media are the ones who have disrespected the enemy dead, if anyone did. It is they that should be investigated and punished.
What are the odds though?