Summary:

 If you have an account in spectator mode floating above the unopened shulker box, opening that box causes the spectator to be pushed up as if it were a player in survival.

Steps to Reproduce:
1. Place a shulker in the world; 

2. Get a player in spectator mode to hover right above the aforementioned box;

3. Let another player open the shulker box;

Observed Results:

 The spectator account position will be shifted up.

Expected Results:

 Spectators should not be affected by shulker box opening.

Notes:

See attached video for the demonstration.