That's something different and honestly something like Luma3DS's lock screen will easily lock out kids. Although I would like to add to my previous post. This isn't completely directed at you, but directed at the concern of "Why is it a bad idea to set CTRNAND to priority?"
The reason it would be a bade idea is because it actually opens the user to outside attack. If the user has Luma3DS on their CTRNAND and doesn't have the lock screen setup, then it leaves their system open for someone else to setup that lock screen on them. Since B9S boots from SD over CTRNAND, it's easy enough to fix this by booting the system off a boot.firm stored on the SD card. If the system booted CTRNAND as priority, then the user is basically fucked until NTRBootHAX is released or the attacker releases the system.
So basically this security flaw is something that can be fixed, but then it opens the system to external security flaws.