1 bit register with data flip flop doesn't store bit?
Your table is incorrect. A MUX element selects one of its inputs based on a secondary input. In this case it's a binary mux and load is used to select the input.

If we say that load = 0 means it selects the DFF and load = 1 means that it selects in you shall see that when load = 0 the circuit repeatedly refreshes the previous value, and load = 1 will read the new value from in.