The lower income bracket does not just consist of slum dwellers. It has many more people(maybe some of us too). Residential areas like Huruma, Zimmermann, Kawangware, Kangemi would provide a market for the gas.
Why would a family man earning 25k not consider buying the gas instead of the cumbersome and slow kerosene stove? The one-off cost will deter a few but if people from across the economic divide have been able to buy mobile phones, then this could easily be the answer to better energy for that sector.