Seriously, from the news story I read, one of the doctors said the type of wound Oz suffered would have killed him within an hour or two. Which means he could have been shot, and he escaped, then died. Which would explain why he still had all his stuff.
The “semen” bit was a rumor that never had any basis in fact. It might have started out as a joke that got out of hand. No semen was ever found anywhere on or in Otzi’s body. In fact his nether regions weren’t nearly as well preserved as most of the rest of him.