What ignoramus has decided to require a restart after an update? Imagine busy on your system, work or gaming or whatever, something you do not want to stop, and seeing that there is an update for Bitdefender. For once, it interrupts you in your flow. Then you need to manually start the update, the second interruption. And lastly you need to restart, after the update. Forget you where busy.
Suggestion, perform the update when the user turns of the system, and the required restart will be fulfilled when the user start the system. No interruption at all.