Let's maybe generously assume that the author is not dumb and would carefully choose a license based on his needs and preferences.
Then consider the facts: The work is based on GPLv2 licensed tool (gifsicle), thus subject to the same terms and conditions. Knowing that, one can read the note as a friendly reminder of how the ToS of the Apple store is incompatible with GPLv2. You may have read it as snark, but it's literally just stating a matter of fact regarding a matter the author of the fork can't legally do anything about.
Then consider the facts: The work is based on GPLv2 licensed tool (gifsicle), thus subject to the same terms and conditions. Knowing that, one can read the note as a friendly reminder of how the ToS of the Apple store is incompatible with GPLv2. You may have read it as snark, but it's literally just stating a matter of fact regarding a matter the author of the fork can't legally do anything about.