'NoAI' mobs can be pushed by players

It was marked as resolved in another issue but it still continues to be a problem in-game, setting generic.movementSpeed to 0 doesn't help

What I expected to happen was...:
A horse would be immovable by players and invisible to replicate chairs

What actually happened was...:
The horses were able to be moved by players, breaking the chairs system in map

Steps to Reproduce:
1. /summon EntityHorse ~ ~ ~ {NoAI:1,Variant:7,Silent:1}
2. Walk into Horse
3.Horse should move, and it shouldn't