Popper's Paradox of Tolerance is an investigation of moral axioms, or principles. It is not Science.

So it's okay that it can't be falsified.

Are you saying only falsifiable things are tenable? Axioms (which it is not) are also unfalsifyable. If you change axioms you're in a different system.

Or if you don't like axioms, principles.

Paradoxes are by design, not falsifying?