I think it's a product of cognitive dissonance. These people believe in freedom, as in free and open systems. But Apple freely chooses to make closed systems. But that's cheating, so they want to promote freedom by coercing Apple by law into making the products the way they want them to be. Except that meanwhile billions of people all over the world don't give a fig about all that and quite happily buy these products as Apple designs them. So huge numbers of people are freely choosing to buy things that are closed, and they shouldn't be allowed to do that. It must be stopped, because of freedom.
Plus of course "Open wins every time" tuned out not to be true, which is impossible, so clearly Apple must have cheated.
If I had to hold all that in my head, I'd go a bit bananas too.