Please allow me to inform you that the operating system on a device translates human commands into machine language and vice versa. This is why the operating system determines whether and application is or is not compatible with a device. Rooted phones have different versions of the operating system, but most applications still run the same. However, we can offer no guarantees that BullGuard will work on the operating system that you chose to install on it.
If the user changes the operating system, no matter how similar it may be to the original one, there will still be differences that may affect the program. Although it is true that the program may work without a problem as well, without proper testing and verifications no one can offer guarantees, therefore we can only recommend the use of the program the way it was built to work, for the platforms it was built to work on.