Can't verify myself, since I don't have any unsigned drivers to hand at the moment, but based on the following (highlighted) segments from the article you have correctly identified & found
Installing unsigned drivers only works when HII runs in WinPE. In WinPE, HII calls DISM to install the drivers and passes the /forceunsigned switch in the DISM command line if you've selected this option. However, DISM does not allow installing drivers in a live Windows environment so HII running in Windows does not use DISM. Windows API is used instead, and Windows API does not provide a way to install unsigned drivers.
... the limitations are set by the OS API's / DISM, not LANDesk. So as such, you're not likely to see any change in behaviour here with LD 2016 since we can't change the way Windows works.
Hope that helps.