Motion-Tag does not work with NoAI-Tag

Mobs without an AI or Armorstands with NoGravity:1 will not be affected by the Motion-Tag

Steps to reproduce:

1:
Summon a mob with no AI.
For example: /summon Slime ~ ~ ~

{NoAI:1}

or

Summon an ArmorStand with no Gravity.
For example: /summon ArmorStand ~ ~ ~

{NoGravity:1}

2:
Add the Motion-Tag. With /entitydata or in the summon-command doesn't matter.
For example: /entitydata @e[type=Slime]

{Motion:[0.0,3.0,0.0]}

or

For example: /entitydata @e[type=ArmorStand]

{Motion:[0.0,3.0,0.0]}

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I don't know if this is intended, because mobs without an AI will not be affected by gravity at all. But I aspected that they will move