Right, and that's what the rest of my sentence was meant to convey. However, the author goes to great extent to obfuscate this fact, as this faq demonstrates: https://git.savannah.gnu.org/cgit/parallel.git/tree/doc/cita...
Not once in that 2000-word rant does Ole outright state that citation is entirely voluntary, and not a condition of the license. Instead, he describes the notice's "GPLv3 compatibility" in a way that incorrectly states you must either respect the license notice or treat the software as it is not open-source. He also responds with vitriol to people who do choose to fork his software, as evidenced here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=905674
I wouldn't have a problem with the program's current behavior if it simply made you type 'i understand' instead of 'will cite', and made clear that it was a non-binding request. As is, the program attempts to sound like a license agreement while Ole insists to maintainers it is not.