It is supposed to. No drone gives you free supply effects. As previously said, Brutus is an "eco" drone, you use it to save supplies. That doesn't mean supply consumption stops entirely, it just slows down (with relation to the supply consumption of other drones such as Hyperion and Booster), which helps in a net supply inflow over time. Regardless of which supply you use while Brutus is equipped, one unit is consumed per key-press. Read the wiki for more info: https://en.tankiwiki.com/Drones