Don't you get a loss of the VCEsat voltage which is often .2 or .3v?
Well as I understand it.
The REG711 draws approx 100mA at its input and to put the transistor into saturation would therefore require approx 5-10mA of base current.
Assuming 5mA Base current and input voltage=1.9V min, then:
Rb = 1.9-1.8/.005 = 20 ohms
When 14 volts is applied to the input then you would be drawing 0.6A through the resistor = 7Watts dissipation plus the Zener dissipation = 0.6W
In any case the Vce Saturation voltage is going to be around 0.3V which makes your input to the REG711 at 1.5V which is below its guaranteed working voltage.