While private land owners dont own the wildlife, i do have sympathy for folks who manage their land for wildlife who are impacted by trespassers and poachers. They have limited recourse. No idea on the case with this particular landowner but if I were a rancher who gave up a bunch of feed, supported habitat, provided sanctuary, at a very real cost to maintain solid wildlife populations and good hunting - i'd want some damn teeth to punish people who trespassed and killed a 370 type bull as well.
If it was just a free for all for hunters on the place, that bull likely wouldn't have existed as he did.