I suggest if he's out of the woodwork you tie shoelaces and ask him if you can put that into the help menu / about or something so it travels with the code and avoids annoying Murphy's Law scenarios later.
"Whatever you want" sounds very close to the thing on my Turbo Processor with fancier language "Copyrighted by ____, with all rights to continue further work with no royalties" or something. If he wants to release copyright, you need another message and another line in the About section.
The irritating thing is Software has a different culture than Movies, but Copyright has become the beast it is by them.