(THEORY QUESTION) If a diode was not placed in a buck convertor, when the switch is off would the load still be powered on?
The catch diode insures a proper return path for the inductors current. Without the diode there is risk of damage to the MOSFET switch and a greatly reduced output.

There is also a possibility of incorrect polarity at the output, possibly causing damage or drawing excessive current from the source. The diode solves many problems on both the ON and OFF cycle of the MOSFET.

To answer your question,yes, the current would keep flowing from source to load if the MOSFET stayed in an ON state. However Vout would equal Vin with no voltage or current control provided by the SMPS IC.

If the diode is missing, there can be NO current flow if the MOSFET is OFF, as the path has been broken. The capacitor will quickly drain to zero volts.

If the diode is missing and the switch is OFF after being ON, then the stored inductors current will pass through the MOSFET switch, likely destroying it. MOSFET's fail as a short, so it would have to be replaced.