In my option 3 above, the Solo player could have other players on his side as well as opposed to him. There's nothing inherent in Solo-online that says you can never run into other players (either allied or opposed). Most of the time you'd be instanced alone,or in your private group, as per your preference, but in situations where your actions might affect others (e.g. you're exploring a system at the same time as another player, or running a blockade) then you might receive a "PvP possibility" warning. It may never go PvP - the other player might waive his claim, you might agree to share finds, there might not be any other players at the blockade at that point in time, etc. But you'd have to run the risk if you wanted to claim the reward when potentially in competition with other players directly. This seems fair to me.