A couple of points. Therefore it cannot, in general, be interpreted as node inclusion.
Pointers are for pre-transform.
Further, I'm not sure how I would create a stylesheet to do a transclusion. I have no argument with any of this. I think that the inclusion problem should be solved. I volunteer to be on a working group that sets out to solve it. Furthermore, the fact that XML would be handled differently from node-less data types would be another bizarre special case.