When you set the MapContext to a specific CRS (a projected orthographic CRS in my case), and then try to read a georeferenced image in with the same CRS (using WorldImageReader), then it forces a reprojection, even though the source and destination CRS's are the same.
This breaks for orthographic CRS since the orthographic reprojection isn't work anyways... (it fails if just one pixel is not projectable).
The work around I have to use is to first read the world image in, then grab it's CRS and use it as the MapContext's CRS before adding it as a layer. This ensures the mem address of the CRS is teh same, and then it will pass the equals test. However, this doesn't work when trying to use uDig, which doesn't do this work around...