The thing about H2S is, it's every bit as dangerous as HCN, but it has a better PR agent. If you wouldn't take off your SCBA mask in a room full of HCN, "even for just a sec," then you shouldn't do it in a room suspected of being full of H2S either.

The fire chief would have known that H2S is hazardous, but his training unfortunately (and obviously) didn't communicate just how hazardous it is.