Apple can do anything it wants with its software. Just as any person decides who comes into his house, a corporation decides on what terms others can use its software.
The law disagrees with your opinion. And that's a good thing.
Can a person cut your leg off in his house as part of "terms of service"?
If I buy it and fully own it, I should be able to do anything I want with it.
I totally agree and this has always been my problem with the iPad. It’s a great peace of hardware that to this day I can’t fully use for development. I have to resort to _crappy_ solutions like running a VM with code-server and SSH in order to do some work on a device perfectly capable of running stuff on its own, but walled off.