Piglins can have soul fire items forced into their hands since 1.16.2

In 1.16.1, piglins would throw any soul fire items in their hands. but since 20w27a, they don't throw soul fire items forced into their hands anymore.

Run the following command:

/summon minecraft:piglin ~ ~ ~ {HandItems:[{id:"minecraft:soul_torch",Count:1b}]}