The simple steam thruster only has specific impulse of 70ms (for the layman trust me when I say this is low, most propellants measure in the triple digits or more). The reason they are doing this isn't for demonstrating ISRU or colonization technologies, its to demonstrate non-volatile low pressure propulsion and attitude control for rideshares cause primary customers already forking millions for a sat and its ride get nervous about the build quaility of bargain seeking hitchhikers laden with hydrazine.