As of commit 1782827, the Rosalina menu hotkey has been fixed and the devs themselves said they won't make it optional as stated on the Luma github: "This feature was rejected because several key features and programs now rely on Rosalina to function properly, namely, the Homebrew Menu."
I've safely disabled it by doing the following steps:
1. Put the boot.firm of the commit mentioned above or a higher version/stable on your SD Card's root and CTRNAND via GodMode9 or FBI
2. Put your SD Card back in your 3DS and set up your Luma settings if it boots you to the menu
3. Press the default hotkey combo (in this case L+D-Pad down+Select) then go to "Miscellaneous Options" and "Save Settings"
4. Power off your 3DS and put the SD Card back into your computer
5. Download any Hex Editor (such as HxD) if you don't have one and start it.
6. In the hex editing program click File then Open and navigate to SD:/luma/config.bin and open the file
7. Go to offset 1D and edit the byte to FF as shown in this image here:
8. File>Save or just simply Ctrl+S!
Done! You can now move the newly changed config.bin to your 3DS SYSNAND via GodMode9 or FBI under CTRNAND/rw/luma and won't be able to boot Rosalina anymore unless you change the byte again or you delete the config file.
I needed to disable this for young kids I'm setting this up for next week and this is currently the only way I can confirm works. It won't "hide" your usage of CFW like the Kecleon3DS patch did since there's no way to disable the Luma boot menu that I know of. But hopefully someone can make something like that again, would be nice for the reason I've stated.