The Disabled points are not used for the generation of the DSM and the orthomosaic. If the DSM has been generated before assigning points to the Disabled point group, step 3 needs to be reprocessed.
Regarding the DTM, the DTM is generated based on the point cloud classification, and more specifically the points that have been assigned to the Ground and Road Surface point groups. For most of the cases, when all the terrain points are correctly assigned to these groups the DTM and the contour lines generated based on the DTM are accurate.
However, we have noticed that in some rare cases, such as high and wide buildings, the DTM might not be correctly generated even if all the points are correctly classified. Our DTM algorithm seems to be unable to smooth out such buildings. Usually, the problem is that the points at the rooftop are considered as terrain points creating an inaccurate DTM in these parts of the project area.
The workaround for these cases is to assign the building points in the Disabled point group, reprocess step 3 in order to regenerate the DSM and the generate the DTM. Please note that doing this the DSM will not be accurate, but the DTM will be.
In case that you are facing issues or the Disabled points are present in the DSM or the orthomosaic, I would need some more information, such as the version you are using, the PDF quality report, the DSM, DTM and contour lines files, in order to investigate on this.