Assuming that the 125 mV bias voltage is somewhere in the middle of tunnel diode negative differential resistance range (it actually is, as far as I know), the oscillator should work. Furthermore, the characteristic of the used electret microphone must provide some gain at the rather low operating voltage. Cause the buffer is a depletion FET usually, this can be expected for typical devices, I think.
I saw some reports at the internet from DIY experts, that where unable to operate the circuit. But they said the same about a standard transistor oscillator, so I think, it isn't a matter of the circuit.