Nice App...
The shapes you are using are elevation stencils (although you cannot easily discern that from how they are named in the stencil) and therefore they respect scale regardless of the page you use them on.
It is the shape that has the scale behavior, not the page type, all page types have a scale.
When we created our enhanced stencil suite for SI5, we developed clear names for each shape with regard to page type use and scale or icon behavior.
We also unlocked scaling on most all of the really nice plan view shapes that users wanted to be able to resize as icons.
So we know it is possible to unlock the scaling of the elevation stencils within the shapesheet and then use them for the line diagram page. If you choose to do ths, we recommend a copy be made of each shape you want to use in each stencil and rename it so you know it is for the Line Diagram Page and that it is an Icon.
For more on that, see
http://d-tools.us/showthread.php?t=2155
I have not studied the complexity of the elevation shapes, but with their layer of text for MFG, MODEL, COMP ID, I suspect there will be some sizing issues with elements of the shape itself.
We will have a look at a few to see if its feasible and perhaps we can add these to our enhanced stencil suite.
Visio Guy will surely have some insight into the issues with this modification.
Stay Tuned!