MSP430G2231: Flashing with no power - is this reliable?

In another forum I participate in, a guy describes in detail how he tried to flash new firmware to a G2231 in circuit.  He did not bring Vcc over from the Launchpad, just the two JTAG lines and ground, and *unplugged* the battery that powered his circuit.  And it worked.  One explanation offered is that for programming, the line connected to the /RST pin is actively high when it's high, and enough current flows "backwards" through what is normally a pullup resistor on /RST to charge up the capacitor on Vcc enough to power the device for flashing.  Does that sound right?  Well, my basic question is - For a circuit with the recommended 47K pullup resistor on /RST, and a 105 cap on Vcc, is flashing without any other power at Vcc reliable?  This is a relevant question because another circuit I'm working on has a soft power switch, and since the power will not be on when flashing, I was looking at having to bring Vcc over from the Launchpad - so four lines in total.  Not a major problem, but no reason to bother with Vcc if it isn't needed for flashing.