"Don't reupload programs which aren't yours."
I disagree.
If the program isn't available through the creator anymore, first you should contact them to see if they can rehost. From there, I guess rehosting it yourself isn't all bad as long as you provide credit. No reason to let a program go to waste.
If it's still up though, then yeah, don't.
Reuploading with permission is fine by me. In any other case, it definitely isn't. Rehosting without permission should only be allowed if the software was completely abandoned and the original creator is nowhere to be found.