If you want to jump out of the plane, please pick a provider that serves skydivers. Do not try to open the door of a regular plane from a normal airline. Moreover, please do not try to make it illegal to have airlines that don't allow opening the door during mid-flight. It makes flying more dangerous for all of us, especially those who don't happen to have a parachute around.
No one is forcing you to stop loading whatever you want on your phone. Just pick a phone manufacturer that allows that. There is a difference between "I want to load anything on my phone" and "I want to load anything on any phone I choose, even from a manufacturer that specifically caters to people who are quite reluctant to load your code unchecked on their phones".
The question is more: Why the fuck do you care if Apple allows sideloading or not. It is a feature you do not have to use and (if Apple implements sideloading) you probably would need to explicitly activate. Just leave the option off, but instead you are here saying the option should not exist for anyone. Those that are reluctant to use it can just ignore it.
WHY?
I should be able to load anything on any phone THAT I OWN. Even if the manufacturer does not want me to. I bought the Phone. I didn't Rent it. I didn't borrow it. IT IS MY PHONE. Why should the manufacturer dictate what I am allowed to do with the phone?
"My Liberty ends where yours starts." is a great Quote in your bio. Is it just there as decoration or do you believe what it means?
So you want the ideological argument then? Well let's see if we can find the various freedom's borders here.
You deserve the freedom to do whatever you want with you device, of course. Jailbreak it if you want. Or throw it away and get another on the free market.
Apple is a private company. They deserve the freedom to create and market a device with the tradeoffs, features and limitations they see fit. Locked down, if they can manage to. Because they are not selling just a device. They are actually selling access to a bunch of services, a platform, a walled garden if you want, for which the device is the entry point, the interface.
And, finally, I deserve the freedom of choice. To choose between open platforms and closed, safe ones, to have both options on the market.
Like when looking for a home: you can buy in the middle of nowhere (and do what you want), rent (and have very limited rights) or buy in a gated community and have certain rights but not unlimited freedom. Because this is true Liberty: when others can freely choose to do things we don't agree with. Like under Capitalism: you can have communist Coops, but under communism you can't have private companies...
No one is forcing you to stop loading whatever you want on your phone. Just pick a phone manufacturer that allows that. There is a difference between "I want to load anything on my phone" and "I want to load anything on any phone I choose, even from a manufacturer that specifically caters to people who are quite reluctant to load your code unchecked on their phones".