From what I have gathered from mullsey, he has both an ON and OFF button on his interface and doesn't want the logic to run if someone accidently hits the button a second time. For this he would want to use a SR (to hold the pump relay ON) but to also feed the Enable of two buffers which would stop that second button press from happening. He can also send the outputs of the latch to the feedback on his buttons to know the current status of the system.

Your logic does work if he only has one button for ON and OFF but in this case I don't think he has that.