You make a good point that law shouldn’t be applied based off belief.

However, and I’m not saying this in regard to your point but as an independent sidenote, we must remember that Sewer isn’t just someone who believes things, they lead a violent cult. They’ve been repeatedly convicted of affray and violent disorder among other things. Neo-Nazism isn’t some abstract harmless idea, and given their context, these threats are not the same as if you or I performed them.