Few people will buy equivalent external ssd storage for 300-500 and carry it around with them to have access to a second OS.
There is absolutely no reason to believe that they will ever act to increase your ownership of your own device and every reason to believe that you will ultimately have about the same privileges as someone using their employers machine at work while being expected to fall full freight.
It's especially bemusing when you understand that evil maid is almost nonexistent in reality while your actual loss of freedom has real effects now.