I tested this with iron golems and zombie pigman together. Zombie pigman in particular should NOT bounce on soul sand especially when they spawn naturally in the nether anyways.
Steps to reproduce
- Place down soul sand in a 5x5 radius.
- Make a wall that is 2 blocks high on one side of the soul sand.
- Make one part of the wall higher (see photo attached)
- Spawn entities at the highest block. (for example villagers)
- Notice that the entities bounce when they go onto the soul sand.