I think you've hit the nail on the head. Scrooge is a lone prospector who's just gotten very lucky with the help of an obscure legal ruling and a lot of support from a wealthy patron who happens to have taken a shine to him as he passes through.

If he leaves the country, there won't be anyone to support his claim (noting that it's based on him occupying the land continuously) or file his paperwork in court and although he nominally owns a valuable asset, in reality it's going to be hard for him to borrow against it in order to hire any kind of legal support, plus he needs to leave urgently.

Better to take the cash offer than try to fight it out from afar.

I think you've hit the nail on the head. Scrooge is a lone prospector who's just gotten very lucky with the help of an obscure legal ruling and a lot of support from a wealthy patron who happens to have taken a shine to him as he passes through.

His claim on the mine is based on his ownership of the homestead on which the copper vein ends, which in turn requires him to occupy the land continuously in order to remain valid. As soon as he leaves, someone else will move into the homestead and the claim to the mine will be theirs and not his.

Now, he could theoretically hire a passel of fine lawyers to defend his claim in his absence (noting that he does nominally own a valuable asset that he could at least try to borrow against) but in reality he's got no ready cash plus he needs to leave urgently.

Better to take the cash offer than try to fight it out from afar.