This is very much along the same lines of thinking. However, there might be some slight differences. See if this helps.
Let's take the example of sending a contract.
The sending role would be "contractor". The action of "sending" is an action that must be initiated by the role. The "contract" is what is sent to yet another role of "customer". Now that action of "sending" can be enabled by a technology (email, snail mail, courier, shared work application, whatever.) So the contract is a product (which we call a deliverable in VNA). I propose that services are also deliverables, not roles. In that sense they would be closer to how I believe you and Clayton Christensen would define a product.
So if I get a massage (which would be really nice about now), that massage is a service. In VNA the role that delivers that service is the "masseuse." The "massage" is a service package that that role delivers to me the "customer." Therefore the "massage" is the deliverable. If you want to get really technical they deliver the "massage experience" which includes a whole lot of things, including value enhancers such as cushy robes and slippers, nice smelly things and so forth.
Now this perspective does not completely negate your quote from Christensen, but it does drill it a bit deeper into what a product or services really is in terms of deliverables, which is the value of using VNA to actually model that. The language of "roles" and "deliverables" forces people to be very specific about exactly what it is they (in their specific roles) are really delivering and to whom. It thus drives the accountability for that deliverable to a finer level.
Not sure if this helps. These perhaps are very different ways of looking at the issue. Both can be valuable. We have just found over time that that making distinctions between a "product" and a "service" can be very difficult because they overlap so much. Products have mini "services" packed into them and services often require products for their delivery. The more generic of "deliverable" seems to sidestep many of these issues. | 
