I think these would do well in the BSS. Most shoppers in the BSS are regular consumers who would be attracted to these books (and titles like The Science of Black Hair may appeal to professionals as well).
They'd also be a good product since they would sell for a relatively higher price vs. the amount of space they'd take up. They would be complimentary vs. competing products with what they already have (people can only use so much shampoo or conditioner, but books would be a new category that people can buy in addition to the other products, not instead of them). They would make a good gift, and the BSS has few gifty products (eg. bath kits, nail art kits - you aren't going to buy someone a box of relaxer or hair color as a gift)- adding another gift item would attract gift dollars that would otherwise go elsewhere. Plus, as these books encourage DIY, it would theoretically increase the amount the customer is spending at BSSes vs. salons.
I would start with a few titles - Ultra Black Hair Growth (very appealing name- more titles should focus on length, imo), Science of Black Hair, Curly Girl, and go from there. I wonder why they don't do this already? It's a good idea.