If there was a safe walkway that you chose not to use, why should he be liable?
People are liable for accidents that occur on their property if the accident was due to THEIR negligence, not yours. Or, if you were on his property with his permission, his homeowner's insurance might cover your injuries; but you were not. By your logic, if you got a ladder and climbed up on the roof and jumped off, he would be liable for your injuries.
You're lucky he doesn't have you charged with trespassing.