By using any P-Channel as a HIGH side switch (meaning Drain is connected to Power side) the base of PMOS voltage is reduced to GND for driving it unlike the NMOS as a HIGH Side Switch which requires gate voltage greater than Source voltage+ few additional volts for driving it.
Beagle Bone boards have a limitation : NO PINS ARE TO BE DRIVEN UNTIL AFTER THE SYS_RESET LINE GOES HIGH.