Inconsistent Scuttle Crab Debuff

Since the introduction of the scuttle crab to the game I have been under the impression that the scuttle crab's Armor/MR debuff only occurs upon it facing "hard CC" and not by slows and fears.

I recently, however, discovered that the scuttle crab's debuff takes place when it is feared by Shaco's boxes.

I'm wondering, is this a bug with its interaction with Shaco's boxes or is this a bug with other champion's (Hec, FIddle, Noc etc.) fear abilities not properly debuffing the scuttle crab?

Would appreciate any responses and would love to hear from someone from Riot.

As a Fiddle main it's a nightmare to kill that little crab!

Thanks!