You may find the reasoning here interesting: https://github.com/kholia/OSX-KVM
The "secret" Apple OSK string is widely available on the Internet. It is also included in a public court document available here. I am not a lawyer but it seems that Apple's attempt(s) to get the OSK string treated as a trade secret did not work out. Due to these reasons, the OSK string is freely included in this repository.
That repo has been around for many years.