Originally Posted by BZ0RG
Yes: Statusbar tweaks > QuickSettings management > Satusbar QuickSettings tiles.
Tick what you want to protect on locked screen there.
Oh, wow! Thank you so much for that. You have no idea how long I've been searching for something like this, and it was there on my phone all along LOL
It just wasn't obvious from the GravityBox menus that that's what those settings were for; I thought it was for hiding tiles altogether.
This is good enough for me, but just out of curiosity, is there a way of not disable those QS tiles completely on the lock-screen, but instead have the phone prompt for credentials when trying to toggle them?