No, they don't. The GNU license isn't public
domain,
I know that the GNU stuff is hardly public domain, but
I thought the document must say something that states
"I, my-name, being of sound mind and-other-legal stuff
do hereby legal-words-for-hand-over all-those-legal-words
for-the-full-set-of-rights to whoever", which at least
gives you a starting point for how to work out what you want
to hand over. I presume that there's a whole bunch of
different rights and what nots that the executor wants to
give up without incurring any liabilities etc.
Antonio