So I was thinking about the big plot hole in "Time Is Money"--that Scrooge would still have to pay Glomgold for the island even after changing the past (assuming that graffiti carved in rock really constitutes legal proof of ownership and disregarding the fact that in that case, Glomgold would never have bought the islands in the first place--your brain will hurt if you think too much about this). The big reason for this, of course, is that the writers wanted for there to be this conflict, so there was gonna be this CONFLICT, dammit. But I wonder if there might also be an element here--conscious or not--of feeling as though it would somehow be "unfair" of Scrooge to just snatch the island away from Glomgold like that, even though Glomgold screwed HIM over first by terraforming it away from him--as we know, Ducktales Scrooge is a good deal "softer" than Barks Scrooge. The time travel business makes all this extremely difficult to parse, but it doesn't seem wholly implausible--they could even have made it make sense, sort of, if they'd had some sorta confrontation between Scrooge wanting to just TAKE the island and HDL insisting that, no, you must pay, it's the right thing to do!
If we're talking about "ethics," exactly how ethical would you say it was, on a scale of one to ten, for Scrooge to buy Glomgold's island at a (comparatively) low price, knowing (via some sort of espionage, we can only assume) that it contained awesomely valuable diamonds, and that Glomgold didn't know this? Pretty dick move, Scroogie! The interesting thing is that I'm pretty sure that it never even occurred to the writers that this was an extremely ethically dubious thing to do. Why is that, I wonder? Why do some ethical breaches bother the writers extremely, whereas others go unnoticed?
I don't think I can provide a satisfactory answer to that here, but I'm sure there are multiple factors. For one, this is a cartoon, and the emotional aspect of this--with Scrooge as "good" and Flinty as "bad"--can override a lot, even if the writers DO sometimes play up Scrooge's ethical lapses (if only to have him overcome them). There's also the eternal contradiction between Scrooge's "making it square" mantra and the fact that, come ON, nobody could possibly make that much money "square" (the question of whether anyone having that much money, regardless of how they got it, could possibly be moral is just a part of that)--and there are plenty of places in Barks where his behavior is clearly in conflict with the idea of "squareness" anyway. This tension is part of what makes Scrooge such a great character, but it doesn't work as well in the Ducktales context, in which Scrooge is a much softer, fuzzier character than he is in the Barks tales of old. The writers thusly try to dissolve the tension, but with Scrooge's fortune still right there front and center, it remains, only it becomes lopsided and can feel dishonest on occasion.