It has everything to do with it. Computing freedom is paramount. We should be able to install whatever software we like on our machines. Therefore it follows that corporations shouldn't be able to discriminate against us for doing so.
Your comment was essentially "but you can exercise your freedom if you want to". I said they will discriminate against you for exercising your freedom, robbing you of choice. "Whatever software you want", provided they belong in the set of software approved by Google or Apple.
If you still don't see how it's related, I don't know what else to say.
Then for your sake I hope they don't find out about those apps. It is their device, after all. They don't like it when you do things they didn't approve of. Their methods grow ever more sophisticated. Hardware cryptography is only the latest innovation.
Things like remote attestation should be illegal.