Assuming for the purposes of debate that the video is genuine, it is likely the military will rapidly administratively discharge him as unfit for service.... a process variously referred to through the years as "chaptering out" or "Section 8'ing".
The military has considerable experience and interest in this, and there is no need to keep the cards and letters rolling in.
This hardly reflects on the entire Marine Corps..... well, unless you already hate the Corps and are looking for a cause celebre to justify and trumpet your biases. The military, after all, draws recruits from society..... and there are all too numerous instances of this type of thing reported every day in civilian America..... lately to child victims more than animals.
If Mr Motari is guilty, yet wants to continue puppy killing without all the criticism, he should leave the Marine Corps and instead join al Qaeda, Hamas or Hezbollah....... they have an amazing and consistent record of cold blooded murder and mayhem - as organizations - and yet one sees no petitions about them. C'mon folks, that market bombing exploiting the two mentally challenged women had to have killed some animals (as well as people)........
Where's the outrage?