Sitting sniffers can be pushed and have leads pull them

The Bug:

Sitting sniffers can be pushed and have leads pull them.

Steps to Reproduce:

1. Summon a sniffer and wait for it to begin digging.

2. Attempt to push the sniffer by colliding with it, or attach a lead to it, and attempt to pull it in your direction.

3. Take note as to whether or not sitting sniffers can be pushed and have leads pull them.

Observed Behavior:

Sitting sniffers can be pushed and have leads pull them.

Expected Behavior:

Sitting sniffers would not be pushed and have leads pull them, following like behavior of similar entities such as camels.