voltage regulator

"Probably." I've never checked. I assume you mean the disconnected regulator is what you are describing

With the field wires disconnected, NEITHER alternator field terminal should show continuity to ground. That is why it's properly called "isolated field."

The way it works is that there is a big transistor in there that for lack of better, controls the "amount of ground" on the green wire. That is the field receives 12V on the blue field wire, goes through the field, and the regulator completes the circuit to ground, and controls that

For the purists, of course, electron flow is opposite direction, but above is the complete 'path'