Man, this is going to seem like I'm coming at you, but truly, I'm not. Again, you bought a product, knowingly, that had a limited warranty. And you're complaining because they won't back it up with a full lifetime warranty. You don't have any right to fuss about what that. They didn't trick you into buying it. Like others have said, it is what it is and you surely can't go buy another similar scope for what they're wanting to charge you to repair that one. They've told you what they have found, what needs to be corrected, and how much it would cost. They don't owe you a technical explanation of anything. It's either a yes or no answer from you. To me it sounds like it's a situation where obviously they have to disassemble the scope, so they're going to go ahead and correct other possible issues while they're in there. That's their way of covering their ass, if all they did was repair the tracking issue and they send it back and other stuff comes up, well then you're mad at them about that too.
Lifetime warranty is sort of a misnomer nowadays. Many items are a limited lifetime warranty, and there is a difference in the terminology. Lifetime warranty usually means for the life of the owner. Limited lifetime warranty means for the life of the product, and that is set by the manufacturer. Some states do have regulations regarding what a limited lifetime warranty is. For example, I work in the furniture industry, and in some states, items with a limited lifetime warranty, that is a period of 7 years.
You can compare all you want to the American companies that offer a lifetime warranty. Like Form said, it's built into the retail cost to the consumer. That alone should tell you what the markup margin really is on those optics.
I'm not saying the situation doesn't suck and that I wouldn't be upset if I was in your shoes. But again, you went into that situation knowingly when you purchased the scope.