Linux isn't POSIX compliant, and as far as I know has no plans to ban newlines in filenames, or even add an option to disable newlines.
In past, there have been Linux-based operating systems that have been certified as Single Unix Specification compliant, and part of said specification is POSIX. I would imagine GNU and Busybox and Musl will be willing to implement the changes proposed by POSIX 2024, which inevitably leads down the road of newlines being banned.
Howw would that work? Checking strings passed to open and rejecting them? Would we then have undeletable files, as we can't refer to their filenames?
I know Linux allows newlines in filenames, but every time I hear it I want to drink.