The event block still contains something when placed in a level, just like the butterfly or the TNT powerup that can be partially interacted with because it was not fully removed from the game.
I believe it can still hurt your character. The main point is that it can be shot, and with the ice weapon, frozen as usual. Just before it "defrosts" the sprite is shown clearly for a moment, and then it becomes invisible again.
Evidently, you wouldn't have been able to freeze this in the real game because you were to fight him without your weapon.