That's a brand new excuse, Apple refused to distribute GPLv3 when GPLv3 was first published, 20ish years ago. How is GPLv3 incompatible with their system volume, yet GPLv2 is still fine?
https://www.gnu.org/licenses/gpl-3.0.en.html#section6
(There are other issues with GPLv3 which make it a dubious choice for companies like Apple, but this one is particularly problematic.)