The way I read your link, the baking soda should go into the washer ... not the dryer. I suspect the baking soda was directly linked to the dryer fire.
of course, the article meant for the baking soda to go in the washer, but you know how details get lost when passed from one person to another.
i'm not sure how baking soda could have caused that fire directly. it's not flammable, instead merely decomposing into water, carbon dioxide, and sodium carbonate (which is the primary ingredient for washing soda).
i'm leaning more towards the customer not washing a wet sleeping bag, which had ungodly amounts of outdoorsy debris stuck to it because it was wet, and the debris igniting from the heat.
sitting down doing paper work about 430 today at store #3 and smelled strong odor of marijuana. Checked the bathroom, no odor, outside, no odor, other side of store, no odor, dryers where i was sitting near, strong odor. Opened 1 nothing, opened 2, BINGO. Customer had left plastic bag of about 5 grams in his pocket in ziplock bag. Bag was melted, weed was gone, attendants were smiling and eating ice cream.