Is it intended that Villager Iron Golems do not attack Screaming Goats, if the Screaming Goat attacks the Golem, not even when the goat attacks a Villager?

You can try it.

/summon minecraft:goat ~ ~ ~ {IsScreamingGoat:1b}

is to spawn the Screaming Goat

and

/summon minecraft:iron_golem

for the Iron Golem