Freedom of movement is more than just visa opt-out. It’s legally almost impossible for an EU country to prevent a citizen of a different EU country from moving there. They would need to arrest you for terrorism or something equally dramatic.

The ECJ has consistently ruled that the freedom of movement is very broad.

I know this because it creates an interesting corner case where Swiss citizens don’t have quite the same broad freedom of movement since ECJ rulings don’t automatically apply to non-EU citizens. For example, an EU citizen can move to Greece for no reason at all and just sit on a beach. A Swiss citizen cannot, and has to find work in 3-6 months or leave.