The lion was NOT hefker – he was owned. He was property, and not that of the hunter. He had a permit to kill a wild lion, not a privately owned one. Unless he was drunk, he should have noticed the lion was not acting like a wild savage beast but like a tamed domesticted one that was used as a tourist attraction (normal wild lions go to great lengths to avoid humans – which is why the goyim consider it a test of skill to catch one).
If an American had gone to Zimbabwe, or anywhere else for that matter, and shot some person for sport he would have been confronted by much than outrage. In the US, had he show someones pet or livestock for “sport” he would have caused outrage, and would have been sued and perhaps arrested.