You are correct on all counts. The problem with the disc version of TS2 is that it relies on DRM methods that are no longer supported. The Origin based UC, now available only to those who already have in on their accounts, was remastered to work on modern operating systems. It's still there for download and install for those who have it, but those who do not cannot obtain it.
The Mac version of TS2 I believe is being kept up to date for the modern macOS and is still available for purchase from the company that was licensed to convert it by way of the App Store. But that doesn't really do any good for a Windows user.
