Fortunately for me, that one line can only make some unwanted features to my OS.
By entering bcdedit /set {bootmgr} displaybootmenu no you will remove operating system selection menu and you will not be able to use secondary OS (if any.)
You will also be able to start your current OS in safe mode on several ways, or start system repair process...
As I can confirm, Disable Safe Mode allows me to select secondary OS...so it is obviously something more than one line of code.
Regards