"I don't see any argument on the xpdf site that justifies the restrictions on what may be done with
There is no need to justify that -- whether the restrictions are justified or not is not the point at all.
" I imagine most people here would agree that the GPL's restrictions are reasonable, but that trying
to prevent someone from copying text from or printing a PDF is just dumb."
Yes, and in other places, most people would agree that the GPL's restrictions are just dumb. Just
because you make GPL software and don't produce encrypted PDF's makes you right in feeling that
you need to enforce the one and discard the other; because if you have that right, then anyone else
has the same right to make their own judgment calls. And use your GPL'ed code in their proprietary