This only applies to the 20th anniversary rules but there are a couple of points there that would pretty much prevent conclusion 4.
From M20, p469-470:
As rough guidelines, however, the Storyteller can assume that most
forms of magick (in the Digital Web) are coincidental, with the following exceptions:
- Effects or gates that jump between sectors or that attempt to bridge the Web with other areas of the Otherworlds. With the
exception of hot links – which have been specifically designed to
pop folks back and forth between locations – an Effect that tries
to open new passages from one sector to another, or from the
Digital Web into some other Realm or Umbra, is considered vulgar
with witnesses… the witness in question being the Web itself.
- Effects that jump from Netspace to Meatspace… because it’s one thing to watch something morph onscreen, and another thing entirely
to watch your computer turn into an asparagus.
Furthermore the rules on Sanctums don't appear to allow for virtual versions, M20 p323 states:
Oh, this place still exists on the Earthly plane, and it’s subject to
the Paradox Effect.
In addition on the following page:
All Effects cast within the Sanctum are considered coincidental
magick, so long as those Effects follow the definition of reality
within that sanctuary.
I also dug out a copy of the Digital Web 2.0 to see how this was handled in the revised edition and that also has the same restrictions:
Effects that jump from Netspace to RealSpace. If Shiba flexes her VR
muscle to blow up a computer in Missis- sippi, her workings are
considered vulgar... usually with witnesses. (A Sleeper might accept a
cool morph, but would be nonplused if it was her computer that did the
So firstly, as far as the 20th anniversary rules are concerned you can't have a Sanctum within the Digital Web. However assuming a generous Story Teller allows it there is still the issue of effects only being Coincidental when cast within the Sanctum, casting from outside the Sanctum is not automatically Coincidental.
Secondly effects that go from Netspace to Realspace are almost always considered Vulgar, regardless of original source.
In conclusion, the rules do not support the conclusions in the question in any way and even bending the rules a fair bit shouldn't support premise 4. It's much like a Mage having only the Entropy sphere and attempting to have every effect count as Coincidental.