If I bought the DVD and download a copy off torrent. There is a case to be made that this download is not a copyright infringement. So, why should I have a concern about uploading?

That is, other people may have fair use claims to the access. So why should I be on the hook for uploading.

—yes, I know the position that RIAA takes on this. I just found it interesting seeing this from a different perspective.

This is no defense at all. You can't say "Yes, I knew there was great likelihood it was wrong, but I didn't know it for a fact that it was wrong, so I was actually in the right." It's a bit like punching somebody in the face and then saying, "Well, how was I supposed to know he didn't want to be punched? Some people like to be punched!"

If you can circumvent copyright just by not caring whether you have a right to copy, that's essentially the same thing as copyright not existing at all.

Unless you're using a private tracker with a minimum ratio requirement you don't need to seed to download something with bittorrent.