The only time a filter bypass valve can open upon a dry start-up (talking about a bone dry filter here or partially drained galleries & filter) vs not doing so with the filter and oiling system 100% filled with oil, is if the oil pump is putting out enough flow through the filter at the low start-up RPM before the back pressure is achieved back to the pump to make the pump hit pressure relief and regulate flow. Even when that does happen, it's a very short bypass event at the filter. IMO, not many engines are going to do that unless the oil is very cold and thick at start-up since filter dP is highly dependent on both oil flow and viscosity. Oil getting cold and thick enough will even cause filters to bypass some on cold start-ups even if no oil leaks out of the system from a bad ADBV and it remains 100% full. Simply increasing engine RPM shortly after a cold start if the oil is cold enough can cause the filter to bypass - so it's always wise to keep the RPM down until the oil warms up a bit.
So we agree that ADBVs can impact startup bypassing and that a well functioning ADBV is better than a poorly functioning one
