The only reason I can think of for why people normally choose the unsulphured molasses is because it is the easiest one for most of us to find. Just go to the supermarket's baking section and there it is.Hi SmokingWings, It's tough to forget things and I've forgotten this one. I'll get back to you when I recall why sulfured molasses isn't the one we normally choose. There is a reason. Sounds like you beat it though.
I would bet good money that the majority of us are living closer to a supermarket (unsulphured molasses) than we are to a farmer's co-op or farmer's supply business (sulphur added molasses). Eventually, many of us started to figure that what we bought in the store that sold food for human consumption had to be better than something bought for feeding animals and soil bacteria.
Enjoy the day.