Sure, but, consider that murdering someone and getting away with it are two different things entirely.i mean they wouldnt have to flee from hunter if he goes for a nice long vacation in the woods. mc has a gun for christs sake.
We know that Hunter doesn't like to leave a trail and if I remember correctly how he put it he "legally doesn't even exist", that doesn't mean no one knows him, and an old guy going missing without a body found is still incredibly suspicious, both to the authorities but also the Ophelia who'd probably want to go to the funeral. Is Hunter really the type to go out hiking? That'd be so cliché and Ophelia would file a missing person's report before the end of the day and that'd be it for MC.
Maybe you could think MC gets all the evidence he needs on Hunter in time? But then you'd still get all kinds of trouble as it'd still be murder, and it wouldn't be direct self defense either.
Ophelia would probably prefer going to the authorities any time over actually committing murder.