It works exactly the same now in bg3. If your character stays next to the ladder it will block the passage. Experienced it in a fight with Polma and Gut yesterday.
Except in BG3, the goblin uses a roaring thunder arrow to force throw your tank away, and likely off a cliff, then climbs the ladder and shoves your other character off the roof and off a cliff too - all of which there is precious little you have any ability to do anything about, because they rarely fail to shove casters and there's no save on being thrown by the roaring arrows, even if they miss you entirely.
