In this case, leaking molten sodium merely causes a nontoxic metal fire. Definitely in the category of "not fun", but not the end of the world either. Just dump some sand on it and wait for it to cool down.

Leaks of molten salt nuclear fuels are an entirely different category of industrial disaster. A nuclear accident at best, and a large-scale disaster at worst.

It's like the difference between a water truck having an accident and spilling water on the road and a damn bursting and flooding a city.

One makes for a funny picture on Reddit, the other gets the national guard called up to deal with the emergency. Both involve spilled water.