The 20w46a article mentions the following:

CHANGED CONDITIONS

SCORE

entity parameter has now been replaced with target.
It can either contain value from old entity field (like this) or be an score holder name in form {"name": "..."}.

There is no loot table condition score. Maybe it was intended to rename the entity_scores condition to score? The entity_scores condition also still has the entity parameter, it hasn't been replaced. The only place where you can use a score holder is in the number providers.

So either the article is wrong or the game is wrong.