But this "clause" is not part of the License for "work A"! The License is a separate text file in the source directory. This "clause" is just a comment embedded directly in the source files. If you use the code to copy work B, you are not breaching the "license" of work A, only "breaching" (whatever that means) this "clause". A more logical view is that this is not a "clause" at all, just a clarification to the user about what is and is not allowed.