Now, I'm not taking one side or the other, here, but I think by "connected" he means joined, which implies that there's no isolation between earth-ground (E_GND) and circuit GND or COM. That answers your question, doesn't it?

That was what I suspected early on, BTW, and was the reason I suggested the AC-coupling rather than DC-coupling between circuit GND and frame-gnd (earth).

In that light, would you say your question is answered?

RE