All mobs riding on saddled striders can control the striders

Zombified piglins can control a strider to be able to attack the player when antagonized. The only way a player can control a strider is by using warped fungi, which the zombified piglins don't have. So the striders should not be able to be controlled by the zombified piglins.

Since 1.16.2 Pre-release 2, zombified piglins now spawn on top of stiders with Warper fungus on a stick in hand. While this is a partial solution, summoning a strider using

/summon minecraft:strider ~ ~ ~ {Passengers:[{id:zombified_piglin}]}

still allows the zombified piglin to control the strider, despite having no warped fungus.