Steel Watch Titan bugged?

[Blitz-chan]

I was playing with friends and we were fighting the Steel Watch Titan at the end of the Foundry in act 3. We killed him by draining his intelligence to 0, which I didn't even know was possible, but he recieved condition atrophy which led to him dying instantly. The problem is, that after the fight the boss didn't drop any loot. Is that intentional feature or some sort of a bug? I normally wouldn't care that much about it, but we have a ranger in group so we naturally wanted that bow. Also we can't reload since we play in Honor Mode.